Precalculus Examples

$f (x) = 3 \sqrt[3]{x} - 5$ ; find $f^{- 1} (x)$

Step 1

Write $f (x) = 3 \sqrt[3]{x} - 5$ as an equation.

$y = 3 \sqrt[3]{x} - 5$

Step 2

Interchange the variables.

$x = 3 \sqrt[3]{y} - 5$

Step 3

Solve for $y$ .

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Step 3.1

Rewrite the equation as $3 \sqrt[3]{y} - 5 = x$ .

$3 \sqrt[3]{y} - 5 = x$

Step 3.2

Add $5$ to both sides of the equation.

$3 \sqrt[3]{y} = x + 5$

Step 3.3

To remove the radical on the left side of the equation, cube both sides of the equation.

${(3 \sqrt[3]{y})}^{3} = {(x + 5)}^{3}$

Step 3.4

Simplify each side of the equation.

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Step 3.4.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{y}$ as $y^{\frac{1}{3}}$ .

${(3 y^{\frac{1}{3}})}^{3} = {(x + 5)}^{3}$

Step 3.4.2

Simplify the left side.

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Step 3.4.2.1

Simplify ${(3 y^{\frac{1}{3}})}^{3}$ .

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Step 3.4.2.1.1

Apply the product rule to $3 y^{\frac{1}{3}}$ .

$3^{3} {(y^{\frac{1}{3}})}^{3} = {(x + 5)}^{3}$

Step 3.4.2.1.2

Raise $3$ to the power of $3$ .

$27 {(y^{\frac{1}{3}})}^{3} = {(x + 5)}^{3}$

Step 3.4.2.1.3

Multiply the exponents in ${(y^{\frac{1}{3}})}^{3}$ .

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Step 3.4.2.1.3.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$27 y^{\frac{1}{3} \cdot 3} = {(x + 5)}^{3}$

Step 3.4.2.1.3.2

Cancel the common factor of $3$ .

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Step 3.4.2.1.3.2.1

Cancel the common factor.

$27 y^{\frac{1}{3} \cdot 3} = {(x + 5)}^{3}$

Step 3.4.2.1.3.2.2

Rewrite the expression.

$27 y^{1} = {(x + 5)}^{3}$

Step 3.4.2.1.4

Simplify.

$27 y = {(x + 5)}^{3}$

Step 3.4.3

Simplify the right side.

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Step 3.4.3.1

Simplify ${(x + 5)}^{3}$ .

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Step 3.4.3.1.1

Use the Binomial Theorem.

$27 y = x^{3} + 3 x^{2} \cdot 5 + 3 x \cdot 5^{2} + 5^{3}$

Step 3.4.3.1.2

Simplify each term.

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Step 3.4.3.1.2.1

Multiply $5$ by $3$ .

$27 y = x^{3} + 15 x^{2} + 3 x \cdot 5^{2} + 5^{3}$

Step 3.4.3.1.2.2

Raise $5$ to the power of $2$ .

$27 y = x^{3} + 15 x^{2} + 3 x \cdot 25 + 5^{3}$

Step 3.4.3.1.2.3

Multiply $25$ by $3$ .

$27 y = x^{3} + 15 x^{2} + 75 x + 5^{3}$

Step 3.4.3.1.2.4

Raise $5$ to the power of $3$ .

$27 y = x^{3} + 15 x^{2} + 75 x + 125$

Step 3.5

Divide each term in $27 y = x^{3} + 15 x^{2} + 75 x + 125$ by $27$ and simplify.

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Step 3.5.1

Divide each term in $27 y = x^{3} + 15 x^{2} + 75 x + 125$ by $27$ .

$\frac{27 y}{27} = \frac{x^{3}}{27} + \frac{15 x^{2}}{27} + \frac{75 x}{27} + \frac{125}{27}$

Step 3.5.2

Simplify the left side.

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Step 3.5.2.1

Cancel the common factor of $27$ .

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Step 3.5.2.1.1

Cancel the common factor.

$\frac{27 y}{27} = \frac{x^{3}}{27} + \frac{15 x^{2}}{27} + \frac{75 x}{27} + \frac{125}{27}$

Step 3.5.2.1.2

Divide $y$ by $1$ .

$y = \frac{x^{3}}{27} + \frac{15 x^{2}}{27} + \frac{75 x}{27} + \frac{125}{27}$

Step 3.5.3

Simplify the right side.

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Step 3.5.3.1

Simplify each term.

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Step 3.5.3.1.1

Cancel the common factor of $15$ and $27$ .

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Step 3.5.3.1.1.1

Factor $3$ out of $15 x^{2}$ .

$y = \frac{x^{3}}{27} + \frac{3 (5 x^{2})}{27} + \frac{75 x}{27} + \frac{125}{27}$

Step 3.5.3.1.1.2

Cancel the common factors.

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Step 3.5.3.1.1.2.1

Factor $3$ out of $27$ .

$y = \frac{x^{3}}{27} + \frac{3 (5 x^{2})}{3 (9)} + \frac{75 x}{27} + \frac{125}{27}$

Step 3.5.3.1.1.2.2

Cancel the common factor.

$y = \frac{x^{3}}{27} + \frac{3 (5 x^{2})}{3 \cdot 9} + \frac{75 x}{27} + \frac{125}{27}$

Step 3.5.3.1.1.2.3

Rewrite the expression.

$y = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{75 x}{27} + \frac{125}{27}$

Step 3.5.3.1.2

Cancel the common factor of $75$ and $27$ .

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Step 3.5.3.1.2.1

Factor $3$ out of $75 x$ .

$y = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{3 (25 x)}{27} + \frac{125}{27}$

Step 3.5.3.1.2.2

Cancel the common factors.

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Step 3.5.3.1.2.2.1

Factor $3$ out of $27$ .

$y = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{3 (25 x)}{3 (9)} + \frac{125}{27}$

Step 3.5.3.1.2.2.2

Cancel the common factor.

$y = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{3 (25 x)}{3 \cdot 9} + \frac{125}{27}$

Step 3.5.3.1.2.2.3

Rewrite the expression.

$y = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}$

Step 4

Replace $y$ with $f^{- 1} (x)$ to show the final answer.

$f^{- 1} (x) = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}$

Step 5

Verify if $f^{- 1} (x) = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}$ is the inverse of $f (x) = 3 \sqrt[3]{x} - 5$ .

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Step 5.1

To verify the inverse, check if $f^{- 1} (f (x)) = x$ and $f (f^{- 1} (x)) = x$ .

Step 5.2

Evaluate $f^{- 1} (f (x))$ .

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Step 5.2.1

Set up the composite result function.

$f^{- 1} (f (x))$

Step 5.2.2

Evaluate $f^{- 1} (3 \sqrt[3]{x} - 5)$ by substituting in the value of $f$ into $f^{- 1}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{5 {(3 \sqrt[3]{x} - 5)}^{2}}{9} + \frac{25 (3 \sqrt[3]{x} - 5)}{9} + \frac{125}{27}$

Step 5.2.3

Simplify terms.

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Step 5.2.3.1

Combine the numerators over the common denominator.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 {(3 \sqrt[3]{x} - 5)}^{2} + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2

Simplify each term.

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Step 5.2.3.2.1

Rewrite ${(3 \sqrt[3]{x} - 5)}^{2}$ as $(3 \sqrt[3]{x} - 5) (3 \sqrt[3]{x} - 5)$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 ((3 \sqrt[3]{x} - 5) (3 \sqrt[3]{x} - 5)) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.2

Expand $(3 \sqrt[3]{x} - 5) (3 \sqrt[3]{x} - 5)$ using the FOIL Method.

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Step 5.2.3.2.2.1

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (3 \sqrt[3]{x} (3 \sqrt[3]{x} - 5) - 5 (3 \sqrt[3]{x} - 5)) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.2.2

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (3 \sqrt[3]{x} (3 \sqrt[3]{x}) + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x} - 5)) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.2.3

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (3 \sqrt[3]{x} (3 \sqrt[3]{x}) + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3

Simplify and combine like terms.

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Step 5.2.3.2.3.1

Simplify each term.

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Step 5.2.3.2.3.1.1

Multiply $3 \sqrt[3]{x} (3 \sqrt[3]{x})$ .

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Step 5.2.3.2.3.1.1.1

Multiply $3$ by $3$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 \sqrt[3]{x} \sqrt[3]{x} + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3.1.1.2

Raise $\sqrt[3]{x}$ to the power of $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 (\sqrt[3]{x} \sqrt[3]{x}) + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3.1.1.3

Raise $\sqrt[3]{x}$ to the power of $1$ .

Step 5.2.3.2.3.1.1.4

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 {\sqrt[3]{x}}^{1 + 1} + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3.1.1.5

Add $1$ and $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 {\sqrt[3]{x}}^{2} + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3.1.2

Rewrite ${\sqrt[3]{x}}^{2}$ as $\sqrt[3]{x^{2}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 \sqrt[3]{x^{2}} + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3.1.3

Multiply $- 5$ by $3$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 \sqrt[3]{x^{2}} - 15 \sqrt[3]{x} - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3.1.4

Multiply $3$ by $- 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 \sqrt[3]{x^{2}} - 15 \sqrt[3]{x} - 15 \sqrt[3]{x} - 5 \cdot - 5) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3.1.5

Multiply $- 5$ by $- 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 \sqrt[3]{x^{2}} - 15 \sqrt[3]{x} - 15 \sqrt[3]{x} + 25) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.3.2

Subtract $15 \sqrt[3]{x}$ from $- 15 \sqrt[3]{x}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 \sqrt[3]{x^{2}} - 30 \sqrt[3]{x} + 25) + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.4

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (9 \sqrt[3]{x^{2}}) + 5 (- 30 \sqrt[3]{x}) + 5 \cdot 25 + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.5

Simplify.

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Step 5.2.3.2.5.1

Multiply $9$ by $5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} + 5 (- 30 \sqrt[3]{x}) + 5 \cdot 25 + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.5.2

Multiply $- 30$ by $5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x} + 5 \cdot 25 + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.5.3

Multiply $5$ by $25$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x} + 125 + 25 (3 \sqrt[3]{x} - 5)}{9}$

Step 5.2.3.2.6

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x} + 125 + 25 (3 \sqrt[3]{x}) + 25 \cdot - 5}{9}$

Step 5.2.3.2.7

Multiply $3$ by $25$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x} + 125 + 75 \sqrt[3]{x} + 25 \cdot - 5}{9}$

Step 5.2.3.2.8

Multiply $25$ by $- 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x} + 125 + 75 \sqrt[3]{x} - 125}{9}$

Step 5.2.3.3

Simplify by adding terms.

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Step 5.2.3.3.1

Combine the opposite terms in $45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x} + 125 + 75 \sqrt[3]{x} - 125$ .

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Step 5.2.3.3.1.1

Subtract $125$ from $125$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x} + 0 + 75 \sqrt[3]{x}}{9}$

Step 5.2.3.3.1.2

Add $45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x}$ and $0$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} - 150 \sqrt[3]{x} + 75 \sqrt[3]{x}}{9}$

Step 5.2.3.3.2

Add $- 150 \sqrt[3]{x}$ and $75 \sqrt[3]{x}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{45 \sqrt[3]{x^{2}} - 75 \sqrt[3]{x}}{9}$

Step 5.2.3.4

Simplify each term.

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Step 5.2.3.4.1

Cancel the common factor of $45 \sqrt[3]{x^{2}} - 75 \sqrt[3]{x}$ and $9$ .

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Step 5.2.3.4.1.1

Factor $3$ out of $45 \sqrt[3]{x^{2}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{3 (15 \sqrt[3]{x^{2}}) - 75 \sqrt[3]{x}}{9}$

Step 5.2.3.4.1.2

Factor $3$ out of $- 75 \sqrt[3]{x}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{3 (15 \sqrt[3]{x^{2}}) + 3 (- 25 \sqrt[3]{x})}{9}$

Step 5.2.3.4.1.3

Factor $3$ out of $3 (15 \sqrt[3]{x^{2}}) + 3 (- 25 \sqrt[3]{x})$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{3 (15 \sqrt[3]{x^{2}} - 25 \sqrt[3]{x})}{9}$

Step 5.2.3.4.1.4

Cancel the common factors.

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Step 5.2.3.4.1.4.1

Factor $3$ out of $9$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{3 (15 \sqrt[3]{x^{2}} - 25 \sqrt[3]{x})}{3 (3)}$

Step 5.2.3.4.1.4.2

Cancel the common factor.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{3 (15 \sqrt[3]{x^{2}} - 25 \sqrt[3]{x})}{3 \cdot 3}$

Step 5.2.3.4.1.4.3

Rewrite the expression.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{15 \sqrt[3]{x^{2}} - 25 \sqrt[3]{x}}{3}$

Step 5.2.3.4.2

Simplify the numerator.

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Step 5.2.3.4.2.1

Factor $5$ out of $15 \sqrt[3]{x^{2}} - 25 \sqrt[3]{x}$ .

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Step 5.2.3.4.2.1.1

Factor $5$ out of $15 \sqrt[3]{x^{2}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (3 \sqrt[3]{x^{2}}) - 25 \sqrt[3]{x}}{3}$

Step 5.2.3.4.2.1.2

Factor $5$ out of $- 25 \sqrt[3]{x}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (3 \sqrt[3]{x^{2}}) + 5 (- 5 \sqrt[3]{x})}{3}$

Step 5.2.3.4.2.1.3

Factor $5$ out of $5 (3 \sqrt[3]{x^{2}}) + 5 (- 5 \sqrt[3]{x})$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (3 \sqrt[3]{x^{2}} - 5 \sqrt[3]{x})}{3}$

Step 5.2.3.4.2.2

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{x^{2}}$ as $x^{\frac{2}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (3 x^{\frac{2}{3}} - 5 \sqrt[3]{x})}{3}$

Step 5.2.3.4.2.3

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{x}$ as $x^{\frac{1}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (3 x^{\frac{2}{3}} - 5 x^{\frac{1}{3}})}{3}$

Step 5.2.3.4.2.4

Factor $x^{\frac{1}{3}}$ out of $3 x^{\frac{2}{3}} - 5 x^{\frac{1}{3}}$ .

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Step 5.2.3.4.2.4.1

Factor $x^{\frac{1}{3}}$ out of $3 x^{\frac{2}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (x^{\frac{1}{3}} (3 x^{\frac{1}{3}}) - 5 x^{\frac{1}{3}})}{3}$

Step 5.2.3.4.2.4.2

Factor $x^{\frac{1}{3}}$ out of $- 5 x^{\frac{1}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (x^{\frac{1}{3}} (3 x^{\frac{1}{3}}) + x^{\frac{1}{3}} \cdot - 5)}{3}$

Step 5.2.3.4.2.4.3

Factor $x^{\frac{1}{3}}$ out of $x^{\frac{1}{3}} (3 x^{\frac{1}{3}}) + x^{\frac{1}{3}} \cdot - 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 (x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5))}{3}$

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3}}{27} + \frac{125}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.5

Combine the numerators over the common denominator.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3} + 125}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6

Simplify each term.

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Step 5.2.3.6.1

Simplify the numerator.

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Step 5.2.3.6.1.1

Rewrite $125$ as $5^{3}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{{(3 \sqrt[3]{x} - 5)}^{3} + 5^{3}}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.2

Since both terms are perfect cubes, factor using the sum of cubes formula, $a^{3} + b^{3} = (a + b) (a^{2} - a b + b^{2})$ where $a = 3 \sqrt[3]{x} - 5$ and $b = 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{(3 \sqrt[3]{x} - 5 + 5) ({(3 \sqrt[3]{x} - 5)}^{2} - (3 \sqrt[3]{x} - 5) \cdot 5 + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.3

Simplify.

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Step 5.2.3.6.1.3.1

Add $- 5$ and $5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{(3 \sqrt[3]{x} + 0) ({(3 \sqrt[3]{x} - 5)}^{2} - (3 \sqrt[3]{x} - 5) \cdot 5 + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.3.2

Add $3 \sqrt[3]{x}$ and $0$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} ({(3 \sqrt[3]{x} - 5)}^{2} - (3 \sqrt[3]{x} - 5) \cdot 5 + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.3.3

Multiply $5$ by $- 1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} ({(3 \sqrt[3]{x} - 5)}^{2} - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4

Simplify each term.

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Step 5.2.3.6.1.4.1

Rewrite ${(3 \sqrt[3]{x} - 5)}^{2}$ as $(3 \sqrt[3]{x} - 5) (3 \sqrt[3]{x} - 5)$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} ((3 \sqrt[3]{x} - 5) (3 \sqrt[3]{x} - 5) - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.2

Expand $(3 \sqrt[3]{x} - 5) (3 \sqrt[3]{x} - 5)$ using the FOIL Method.

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Step 5.2.3.6.1.4.2.1

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (3 \sqrt[3]{x} (3 \sqrt[3]{x} - 5) - 5 (3 \sqrt[3]{x} - 5) - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.2.2

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (3 \sqrt[3]{x} (3 \sqrt[3]{x}) + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.2.3

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (3 \sqrt[3]{x} (3 \sqrt[3]{x}) + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3

Simplify and combine like terms.

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Step 5.2.3.6.1.4.3.1

Simplify each term.

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Step 5.2.3.6.1.4.3.1.1

Multiply $3 \sqrt[3]{x} (3 \sqrt[3]{x})$ .

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Step 5.2.3.6.1.4.3.1.1.1

Multiply $3$ by $3$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x} \sqrt[3]{x} + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3.1.1.2

Raise $\sqrt[3]{x}$ to the power of $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 (\sqrt[3]{x} \sqrt[3]{x}) + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3.1.1.3

Raise $\sqrt[3]{x}$ to the power of $1$ .

Step 5.2.3.6.1.4.3.1.1.4

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 {\sqrt[3]{x}}^{1 + 1} + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3.1.1.5

Add $1$ and $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 {\sqrt[3]{x}}^{2} + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3.1.2

Rewrite ${\sqrt[3]{x}}^{2}$ as $\sqrt[3]{x^{2}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} + 3 \sqrt[3]{x} \cdot - 5 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3.1.3

Multiply $- 5$ by $3$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} - 15 \sqrt[3]{x} - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3.1.4

Multiply $3$ by $- 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} - 15 \sqrt[3]{x} - 15 \sqrt[3]{x} - 5 \cdot - 5 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3.1.5

Multiply $- 5$ by $- 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} - 15 \sqrt[3]{x} - 15 \sqrt[3]{x} + 25 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.3.2

Subtract $15 \sqrt[3]{x}$ from $- 15 \sqrt[3]{x}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} - 30 \sqrt[3]{x} + 25 - 5 (3 \sqrt[3]{x} - 5) + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.4

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} - 30 \sqrt[3]{x} + 25 - 5 (3 \sqrt[3]{x}) - 5 \cdot - 5 + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.5

Multiply $3$ by $- 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} - 30 \sqrt[3]{x} + 25 - 15 \sqrt[3]{x} - 5 \cdot - 5 + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.6

Multiply $- 5$ by $- 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} - 30 \sqrt[3]{x} + 25 - 15 \sqrt[3]{x} + 25 + 5^{2})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.4.7

Raise $5$ to the power of $2$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} - 30 \sqrt[3]{x} + 25 - 15 \sqrt[3]{x} + 25 + 25)}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.5

Subtract $15 \sqrt[3]{x}$ from $- 30 \sqrt[3]{x}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} + 25 - 45 \sqrt[3]{x} + 25 + 25)}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.6

Add $25$ and $25$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} + 50 - 45 \sqrt[3]{x} + 25)}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.7

Add $50$ and $25$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (9 \sqrt[3]{x^{2}} + 75 - 45 \sqrt[3]{x})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.8

Factor $3$ out of $9 \sqrt[3]{x^{2}} + 75 - 45 \sqrt[3]{x}$ .

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Step 5.2.3.6.1.8.1

Factor $3$ out of $9 \sqrt[3]{x^{2}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (3 (3 \sqrt[3]{x^{2}}) + 75 - 45 \sqrt[3]{x})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.8.2

Factor $3$ out of $75$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (3 (3 \sqrt[3]{x^{2}}) + 3 (25) - 45 \sqrt[3]{x})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.8.3

Factor $3$ out of $- 45 \sqrt[3]{x}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (3 (3 \sqrt[3]{x^{2}}) + 3 (25) + 3 (- 15 \sqrt[3]{x}))}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.8.4

Factor $3$ out of $3 (3 \sqrt[3]{x^{2}}) + 3 (25)$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (3 (3 \sqrt[3]{x^{2}} + 25) + 3 (- 15 \sqrt[3]{x}))}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.8.5

Factor $3$ out of $3 (3 \sqrt[3]{x^{2}} + 25) + 3 (- 15 \sqrt[3]{x})$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} (3 (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x}))}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} \cdot (3 (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x}))}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.1.9

Multiply $3$ by $3$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{9 \sqrt[3]{x} (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x})}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.2

Cancel the common factor of $9$ and $27$ .

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Step 5.2.3.6.2.1

Factor $9$ out of $9 \sqrt[3]{x} (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x})$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{9 (\sqrt[3]{x} (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x}))}{27} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.2.2

Cancel the common factors.

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Step 5.2.3.6.2.2.1

Factor $9$ out of $27$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{9 (\sqrt[3]{x} (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x}))}{9 \cdot 3} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.2.2.2

Cancel the common factor.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{9 (\sqrt[3]{x} (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x}))}{9 \cdot 3} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.6.2.2.3

Rewrite the expression.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{\sqrt[3]{x} (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x})}{3} + \frac{5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.7

Combine the numerators over the common denominator.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{\sqrt[3]{x} (3 \sqrt[3]{x^{2}} + 25 - 15 \sqrt[3]{x}) + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8

Simplify each term.

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Step 5.2.3.8.1

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{\sqrt[3]{x} (3 \sqrt[3]{x^{2}}) + \sqrt[3]{x} \cdot 25 + \sqrt[3]{x} (- 15 \sqrt[3]{x}) + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.2

Simplify.

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Step 5.2.3.8.2.1

Rewrite using the commutative property of multiplication.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} \sqrt[3]{x^{2}} + \sqrt[3]{x} \cdot 25 + \sqrt[3]{x} (- 15 \sqrt[3]{x}) + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.2.2

Move $25$ to the left of $\sqrt[3]{x}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} \sqrt[3]{x^{2}} + 25 \cdot \sqrt[3]{x} + \sqrt[3]{x} (- 15 \sqrt[3]{x}) + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.2.3

Rewrite using the commutative property of multiplication.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x} \sqrt[3]{x^{2}} + 25 \cdot \sqrt[3]{x} - 15 \sqrt[3]{x} \sqrt[3]{x} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3

Simplify each term.

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Step 5.2.3.8.3.1

Multiply $3 \sqrt[3]{x} \sqrt[3]{x^{2}}$ .

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Step 5.2.3.8.3.1.1

Combine using the product rule for radicals.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x^{2} x} + 25 \cdot \sqrt[3]{x} - 15 \sqrt[3]{x} \sqrt[3]{x} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.1.2

Multiply $x^{2}$ by $x$ by adding the exponents.

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Step 5.2.3.8.3.1.2.1

Multiply $x^{2}$ by $x$ .

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Step 5.2.3.8.3.1.2.1.1

Raise $x$ to the power of $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x^{2} x} + 25 \cdot \sqrt[3]{x} - 15 \sqrt[3]{x} \sqrt[3]{x} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.1.2.1.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x^{2 + 1}} + 25 \cdot \sqrt[3]{x} - 15 \sqrt[3]{x} \sqrt[3]{x} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.1.2.2

Add $2$ and $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 \sqrt[3]{x^{3}} + 25 \cdot \sqrt[3]{x} - 15 \sqrt[3]{x} \sqrt[3]{x} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.2

Pull terms out from under the radical, assuming real numbers.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 x + 25 \cdot \sqrt[3]{x} - 15 \sqrt[3]{x} \sqrt[3]{x} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.3

Multiply $- 15 \sqrt[3]{x} \sqrt[3]{x}$ .

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Step 5.2.3.8.3.3.1

Raise $\sqrt[3]{x}$ to the power of $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 x + 25 \sqrt[3]{x} - 15 (\sqrt[3]{x} \sqrt[3]{x}) + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.3.2

Raise $\sqrt[3]{x}$ to the power of $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 x + 25 \sqrt[3]{x} - 15 (\sqrt[3]{x} \sqrt[3]{x}) + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.3.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 x + 25 \sqrt[3]{x} - 15 {\sqrt[3]{x}}^{1 + 1} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.3.4

Add $1$ and $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 x + 25 \sqrt[3]{x} - 15 {\sqrt[3]{x}}^{2} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.3.8.3.4

Rewrite ${\sqrt[3]{x}}^{2}$ as $\sqrt[3]{x^{2}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 x + 25 \sqrt[3]{x} - 15 \sqrt[3]{x^{2}} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.4

Simplify the numerator.

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Step 5.2.4.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{x}$ as $x^{\frac{1}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 x + 25 x^{\frac{1}{3}} - 15 \sqrt[3]{x^{2}} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.4.2

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{x^{2}}$ as $x^{\frac{2}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{3 x + 25 x^{\frac{1}{3}} - 15 x^{\frac{2}{3}} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.4.3

Factor $x^{\frac{1}{3}}$ out of $3 x + 25 x^{\frac{1}{3}} - 15 x^{\frac{2}{3}} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)$ .

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Step 5.2.4.3.1

Factor $x^{\frac{1}{3}}$ out of $3 x$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}}) + 25 x^{\frac{1}{3}} - 15 x^{\frac{2}{3}} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.4.3.2

Factor $x^{\frac{1}{3}}$ out of $25 x^{\frac{1}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}}) + x^{\frac{1}{3}} \cdot 25 - 15 x^{\frac{2}{3}} + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.4.3.3

Factor $x^{\frac{1}{3}}$ out of $- 15 x^{\frac{2}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}}) + x^{\frac{1}{3}} \cdot 25 + x^{\frac{1}{3}} (- 15 x^{\frac{1}{3}}) + 5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)}{3}$

Step 5.2.4.3.4

Factor $x^{\frac{1}{3}}$ out of $5 x^{\frac{1}{3}} (3 x^{\frac{1}{3}} - 5)$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}}) + x^{\frac{1}{3}} \cdot 25 + x^{\frac{1}{3}} (- 15 x^{\frac{1}{3}}) + x^{\frac{1}{3}} (5 (3 x^{\frac{1}{3}} - 5))}{3}$

Step 5.2.4.3.5

Factor $x^{\frac{1}{3}}$ out of $x^{\frac{1}{3}} (3 x^{\frac{2}{3}}) + x^{\frac{1}{3}} \cdot 25$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 25) + x^{\frac{1}{3}} (- 15 x^{\frac{1}{3}}) + x^{\frac{1}{3}} (5 (3 x^{\frac{1}{3}} - 5))}{3}$

Step 5.2.4.3.6

Factor $x^{\frac{1}{3}}$ out of $x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 25) + x^{\frac{1}{3}} (- 15 x^{\frac{1}{3}})$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 25 - 15 x^{\frac{1}{3}}) + x^{\frac{1}{3}} (5 (3 x^{\frac{1}{3}} - 5))}{3}$

Step 5.2.4.3.7

Factor $x^{\frac{1}{3}}$ out of $x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 25 - 15 x^{\frac{1}{3}}) + x^{\frac{1}{3}} (5 (3 x^{\frac{1}{3}} - 5))$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 25 - 15 x^{\frac{1}{3}} + 5 (3 x^{\frac{1}{3}} - 5))}{3}$

Step 5.2.4.4

Apply the distributive property.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 25 - 15 x^{\frac{1}{3}} + 5 (3 x^{\frac{1}{3}}) + 5 \cdot - 5)}{3}$

Step 5.2.4.5

Multiply $3$ by $5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 25 - 15 x^{\frac{1}{3}} + 15 x^{\frac{1}{3}} + 5 \cdot - 5)}{3}$

Step 5.2.4.6

Multiply $5$ by $- 5$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 25 - 15 x^{\frac{1}{3}} + 15 x^{\frac{1}{3}} - 25)}{3}$

Step 5.2.4.7

Subtract $25$ from $25$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} - 15 x^{\frac{1}{3}} + 15 x^{\frac{1}{3}} + 0)}{3}$

Step 5.2.4.8

Add $3 x^{\frac{2}{3}} - 15 x^{\frac{1}{3}} + 15 x^{\frac{1}{3}}$ and $0$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} - 15 x^{\frac{1}{3}} + 15 x^{\frac{1}{3}})}{3}$

Step 5.2.4.9

Add $- 15 x^{\frac{1}{3}}$ and $15 x^{\frac{1}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} (3 x^{\frac{2}{3}} + 0)}{3}$

Step 5.2.4.10

Add $3 x^{\frac{2}{3}}$ and $0$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{1}{3}} \cdot (3 x^{\frac{2}{3}})}{3}$

Step 5.2.4.11

Combine exponents.

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Step 5.2.4.11.1

Multiply $x^{\frac{1}{3}}$ by $x^{\frac{2}{3}}$ by adding the exponents.

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Step 5.2.4.11.1.1

Move $x^{\frac{2}{3}}$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{2}{3}} x^{\frac{1}{3}} \cdot 3}{3}$

Step 5.2.4.11.1.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{2}{3} + \frac{1}{3}} \cdot 3}{3}$

Step 5.2.4.11.1.3

Combine the numerators over the common denominator.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{2 + 1}{3}} \cdot 3}{3}$

Step 5.2.4.11.1.4

Add $2$ and $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x^{\frac{3}{3}} \cdot 3}{3}$

Step 5.2.4.11.1.5

Divide $3$ by $3$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x \cdot 3}{3}$

Step 5.2.4.11.2

Simplify $x^{1} \cdot 3$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x \cdot 3}{3}$

Step 5.2.5

Cancel the common factor of $3$ .

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Step 5.2.5.1

Cancel the common factor.

$f^{- 1} (3 \sqrt[3]{x} - 5) = \frac{x \cdot 3}{3}$

Step 5.2.5.2

Divide $x$ by $1$ .

$f^{- 1} (3 \sqrt[3]{x} - 5) = x$

Step 5.3

Evaluate $f (f^{- 1} (x))$ .

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Step 5.3.1

Set up the composite result function.

$f (f^{- 1} (x))$

Step 5.3.2

Evaluate $f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27})$ by substituting in the value of $f^{- 1}$ into $f$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.3

Remove parentheses.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4

Simplify each term.

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Step 5.3.4.1

To write $\frac{5 x^{2}}{9}$ as a fraction with a common denominator, multiply by $\frac{3}{3}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3}}{27} + \frac{5 x^{2}}{9} \cdot \frac{3}{3} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4.2

Write each expression with a common denominator of $27$ , by multiplying each by an appropriate factor of $1$ .

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Step 5.3.4.2.1

Multiply $\frac{5 x^{2}}{9}$ by $\frac{3}{3}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3}}{27} + \frac{5 x^{2} \cdot 3}{9 \cdot 3} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4.2.2

Multiply $9$ by $3$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3}}{27} + \frac{5 x^{2} \cdot 3}{27} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4.3

Combine the numerators over the common denominator.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3} + 5 x^{2} \cdot 3}{27} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4.4

Simplify the numerator.

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Step 5.3.4.4.1

Factor $x^{2}$ out of $x^{3} + 5 x^{2} \cdot 3$ .

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Step 5.3.4.4.1.1

Factor $x^{2}$ out of $x^{3}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} x + 5 x^{2} \cdot 3}{27} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4.4.1.2

Factor $x^{2}$ out of $5 x^{2} \cdot 3$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} x + x^{2} (5 \cdot 3)}{27} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4.4.1.3

Factor $x^{2}$ out of $x^{2} x + x^{2} (5 \cdot 3)$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} (x + 5 \cdot 3)}{27} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4.4.2

Multiply $5$ by $3$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} (x + 15)}{27} + \frac{25 x}{9} + \frac{125}{27}} - 5$

Step 5.3.4.5

Find the common denominator.

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Step 5.3.4.5.1

Multiply $\frac{25 x}{9}$ by $\frac{3}{3}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} (x + 15)}{27} + \frac{25 x}{9} \cdot \frac{3}{3} + \frac{125}{27}} - 5$

Step 5.3.4.5.2

Multiply $\frac{25 x}{9}$ by $\frac{3}{3}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} (x + 15)}{27} + \frac{25 x \cdot 3}{9 \cdot 3} + \frac{125}{27}} - 5$

Step 5.3.4.5.3

Reorder the factors of $9 \cdot 3$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} (x + 15)}{27} + \frac{25 x \cdot 3}{3 \cdot 9} + \frac{125}{27}} - 5$

Step 5.3.4.5.4

Multiply $3$ by $9$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} (x + 15)}{27} + \frac{25 x \cdot 3}{27} + \frac{125}{27}} - 5$

Step 5.3.4.6

Combine the numerators over the common denominator.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} (x + 15) + 25 x \cdot 3 + 125}{27}} - 5$

Step 5.3.4.7

Multiply $3$ by $25$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} (x + 15) + 75 x + 125}{27}} - 5$

Step 5.3.4.8

Simplify the numerator.

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Step 5.3.4.8.1

Apply the distributive property.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} x + x^{2} \cdot 15 + 75 x + 125}{27}} - 5$

Step 5.3.4.8.2

Multiply $x^{2}$ by $x$ by adding the exponents.

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Step 5.3.4.8.2.1

Multiply $x^{2}$ by $x$ .

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Step 5.3.4.8.2.1.1

Raise $x$ to the power of $1$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2} x + x^{2} \cdot 15 + 75 x + 125}{27}} - 5$

Step 5.3.4.8.2.1.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{2 + 1} + x^{2} \cdot 15 + 75 x + 125}{27}} - 5$

Step 5.3.4.8.2.2

Add $2$ and $1$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3} + x^{2} \cdot 15 + 75 x + 125}{27}} - 5$

Step 5.3.4.8.3

Move $15$ to the left of $x^{2}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3} + 15 \cdot x^{2} + 75 x + 125}{27}} - 5$

Step 5.3.4.8.4

Rewrite $x^{3} + 15 x^{2} + 75 x + 125$ in a factored form.

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Step 5.3.4.8.4.1

Regroup terms.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3} + 125 + 15 x^{2} + 75 x}{27}} - 5$

Step 5.3.4.8.4.2

Rewrite $125$ as $5^{3}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{x^{3} + 5^{3} + 15 x^{2} + 75 x}{27}} - 5$

Step 5.3.4.8.4.3

Since both terms are perfect cubes, factor using the sum of cubes formula, $a^{3} + b^{3} = (a + b) (a^{2} - a b + b^{2})$ where $a = x$ and $b = 5$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} - x \cdot 5 + 5^{2}) + 15 x^{2} + 75 x}{27}} - 5$

Step 5.3.4.8.4.4

Simplify.

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Step 5.3.4.8.4.4.1

Multiply $5$ by $- 1$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} - 5 x + 5^{2}) + 15 x^{2} + 75 x}{27}} - 5$

Step 5.3.4.8.4.4.2

Raise $5$ to the power of $2$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} - 5 x + 25) + 15 x^{2} + 75 x}{27}} - 5$

Step 5.3.4.8.4.5

Factor $15 x$ out of $15 x^{2} + 75 x$ .

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Step 5.3.4.8.4.5.1

Factor $15 x$ out of $15 x^{2}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} - 5 x + 25) + 15 x (x) + 75 x}{27}} - 5$

Step 5.3.4.8.4.5.2

Factor $15 x$ out of $75 x$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} - 5 x + 25) + 15 x (x) + 15 x (5)}{27}} - 5$

Step 5.3.4.8.4.5.3

Factor $15 x$ out of $15 x (x) + 15 x (5)$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} - 5 x + 25) + 15 x (x + 5)}{27}} - 5$

Step 5.3.4.8.4.6

Factor $x + 5$ out of $(x + 5) (x^{2} - 5 x + 25) + 15 x (x + 5)$ .

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Step 5.3.4.8.4.6.1

Factor $x + 5$ out of $15 x (x + 5)$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} - 5 x + 25) + (x + 5) (15 x)}{27}} - 5$

Step 5.3.4.8.4.6.2

Factor $x + 5$ out of $(x + 5) (x^{2} - 5 x + 25) + (x + 5) (15 x)$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} - 5 x + 25 + 15 x)}{27}} - 5$

Step 5.3.4.8.4.7

Add $- 5 x$ and $15 x$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} + 10 x + 25)}{27}} - 5$

Step 5.3.4.8.4.8

Factor using the perfect square rule.

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Step 5.3.4.8.4.8.1

Rewrite $25$ as $5^{2}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} + 10 x + 5^{2})}{27}} - 5$

Step 5.3.4.8.4.8.2

Check that the middle term is two times the product of the numbers being squared in the first term and third term.

$10 x = 2 \cdot x \cdot 5$

Step 5.3.4.8.4.8.3

Rewrite the polynomial.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) (x^{2} + 2 \cdot x \cdot 5 + 5^{2})}{27}} - 5$

Step 5.3.4.8.4.8.4

Factor using the perfect square trinomial rule $a^{2} + 2 a b + b^{2} = {(a + b)}^{2}$ , where $a = x$ and $b = 5$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) {(x + 5)}^{2}}{27}} - 5$

Step 5.3.4.9

Multiply $x + 5$ by ${(x + 5)}^{2}$ by adding the exponents.

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Step 5.3.4.9.1

Multiply $x + 5$ by ${(x + 5)}^{2}$ .

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Step 5.3.4.9.1.1

Raise $x + 5$ to the power of $1$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{(x + 5) {(x + 5)}^{2}}{27}} - 5$

Step 5.3.4.9.1.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{{(x + 5)}^{1 + 2}}{27}} - 5$

Step 5.3.4.9.2

Add $1$ and $2$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{{(x + 5)}^{3}}{27}} - 5$

Step 5.3.4.10

Rewrite $27$ as $3^{3}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{\frac{{(x + 5)}^{3}}{3^{3}}} - 5$

Step 5.3.4.11

Rewrite $\frac{{(x + 5)}^{3}}{3^{3}}$ as ${(\frac{x + 5}{3})}^{3}$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 \sqrt[3]{{(\frac{x + 5}{3})}^{3}} - 5$

Step 5.3.4.12

Pull terms out from under the radical, assuming real numbers.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 (\frac{x + 5}{3}) - 5$

Step 5.3.4.13

Cancel the common factor of $3$ .

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Step 5.3.4.13.1

Cancel the common factor.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = 3 (\frac{x + 5}{3}) - 5$

Step 5.3.4.13.2

Rewrite the expression.

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = x + 5 - 5$

Step 5.3.5

Combine the opposite terms in $x + 5 - 5$ .

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Step 5.3.5.1

Subtract $5$ from $5$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = x + 0$

Step 5.3.5.2

Add $x$ and $0$ .

$f (\frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}) = x$

Step 5.4

Since $f^{- 1} (f (x)) = x$ and $f (f^{- 1} (x)) = x$ , then $f^{- 1} (x) = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}$ is the inverse of $f (x) = 3 \sqrt[3]{x} - 5$ .

$f^{- 1} (x) = \frac{x^{3}}{27} + \frac{5 x^{2}}{9} + \frac{25 x}{9} + \frac{125}{27}$