Algebra Examples

$f (x) = \sqrt[3]{2 x}$

Step 1

Write $f (x) = \sqrt[3]{2 x}$ as an equation.

$y = \sqrt[3]{2 x}$

Step 2

Interchange the variables.

$x = \sqrt[3]{2 y}$

Step 3

Solve for $y$ .

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Step 3.1

Rewrite the equation as $\sqrt[3]{2 y} = x$ .

$\sqrt[3]{2 y} = x$

Step 3.2

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

${\sqrt[3]{2 y}}^{3} = x^{3}$

Step 3.3

Simplify each side of the equation.

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Step 3.3.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{2 y}$ as ${(2 y)}^{\frac{1}{3}}$ .

${({(2 y)}^{\frac{1}{3}})}^{3} = x^{3}$

Step 3.3.2

Simplify the left side.

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Step 3.3.2.1

Simplify ${({(2 y)}^{\frac{1}{3}})}^{3}$ .

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Step 3.3.2.1.1

Multiply the exponents in ${({(2 y)}^{\frac{1}{3}})}^{3}$ .

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Step 3.3.2.1.1.1

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

${(2 y)}^{\frac{1}{3} \cdot 3} = x^{3}$

Step 3.3.2.1.1.2

Cancel the common factor of $3$ .

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Step 3.3.2.1.1.2.1

Cancel the common factor.

${(2 y)}^{\frac{1}{3} \cdot 3} = x^{3}$

Step 3.3.2.1.1.2.2

Rewrite the expression.

${(2 y)}^{1} = x^{3}$

Step 3.3.2.1.2

Simplify.

$2 y = x^{3}$

Step 3.4

Divide each term in $2 y = x^{3}$ by $2$ and simplify.

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Step 3.4.1

Divide each term in $2 y = x^{3}$ by $2$ .

$\frac{2 y}{2} = \frac{x^{3}}{2}$

Step 3.4.2

Simplify the left side.

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Step 3.4.2.1

Cancel the common factor of $2$ .

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Step 3.4.2.1.1

Cancel the common factor.

$\frac{2 y}{2} = \frac{x^{3}}{2}$

Step 3.4.2.1.2

Divide $y$ by $1$ .

$y = \frac{x^{3}}{2}$

Step 4

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

$f^{- 1} (x) = \frac{x^{3}}{2}$

Step 5

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

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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 $f^{- 1} (\sqrt[3]{2 x})$ by substituting in the value of $f$ into $f^{- 1}$ .

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

Step 5.2.3

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

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Step 5.2.3.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{2 x}$ as ${(2 x)}^{\frac{1}{3}}$ .

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

Step 5.2.3.2

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

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

Step 5.2.3.3

Combine $\frac{1}{3}$ and $3$ .

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

Step 5.2.3.4

Cancel the common factor of $3$ .

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Step 5.2.3.4.1

Cancel the common factor.

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

Step 5.2.3.4.2

Rewrite the expression.

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

Step 5.2.3.5

Simplify.

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

Step 5.2.4

Cancel the common factor of $2$ .

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Step 5.2.4.1

Cancel the common factor.

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

Step 5.2.4.2

Divide $x$ by $1$ .

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

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 $f (\frac{x^{3}}{2})$ by substituting in the value of $f^{- 1}$ into $f$ .

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

Step 5.3.3

Combine $2$ and $\frac{x^{3}}{2}$ .

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

Step 5.3.4

Reduce the expression by cancelling the common factors.

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Step 5.3.4.1

Reduce the expression $\frac{2 x^{3}}{2}$ by cancelling the common factors.

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Step 5.3.4.1.1

Cancel the common factor.

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

Step 5.3.4.1.2

Rewrite the expression.

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

Step 5.3.4.2

Divide $x^{3}$ by $1$ .

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

Step 5.3.5

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

$f (\frac{x^{3}}{2}) = x$

Step 5.4

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

$f^{- 1} (x) = \frac{x^{3}}{2}$