Calculus Examples

$x^{3} - 5 x^{2} - 7 x + 9$

Step 1

Find the derivative.

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Step 1.1

Differentiate.

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Step 1.1.1

By the Sum Rule, the derivative of $x^{3} - 5 x^{2} - 7 x + 9$ with respect to $x$ is $\frac{d}{d x} [x^{3}] + \frac{d}{d x} [- 5 x^{2}] + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9]$ .

$\frac{d}{d x} [x^{3}] + \frac{d}{d x} [- 5 x^{2}] + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9]$

Step 1.1.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 3$ .

$3 x^{2} + \frac{d}{d x} [- 5 x^{2}] + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9]$

Step 1.2

Evaluate $\frac{d}{d x} [- 5 x^{2}]$ .

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Step 1.2.1

Since $- 5$ is constant with respect to $x$ , the derivative of $- 5 x^{2}$ with respect to $x$ is $- 5 \frac{d}{d x} [x^{2}]$ .

$3 x^{2} - 5 \frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9]$

Step 1.2.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$3 x^{2} - 5 (2 x) + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9]$

Step 1.2.3

Multiply $2$ by $- 5$ .

$3 x^{2} - 10 x + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9]$

Step 1.3

Evaluate $\frac{d}{d x} [- 7 x]$ .

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Step 1.3.1

Since $- 7$ is constant with respect to $x$ , the derivative of $- 7 x$ with respect to $x$ is $- 7 \frac{d}{d x} [x]$ .

$3 x^{2} - 10 x - 7 \frac{d}{d x} [x] + \frac{d}{d x} [9]$

Step 1.3.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$3 x^{2} - 10 x - 7 \cdot 1 + \frac{d}{d x} [9]$

Step 1.3.3

Multiply $- 7$ by $1$ .

$3 x^{2} - 10 x - 7 + \frac{d}{d x} [9]$

Step 1.4

Differentiate using the Constant Rule.

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Step 1.4.1

Since $9$ is constant with respect to $x$ , the derivative of $9$ with respect to $x$ is $0$ .

$3 x^{2} - 10 x - 7 + 0$

Step 1.4.2

Add $3 x^{2} - 10 x - 7$ and $0$ .

$3 x^{2} - 10 x - 7$

Step 2

Set the derivative equal to $0$ then solve the equation $3 x^{2} - 10 x - 7 = 0$ .

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Step 2.1

Use the quadratic formula to find the solutions.

$\frac{- b \pm \sqrt{b^{2} - 4 (a c)}}{2 a}$

Step 2.2

Substitute the values $a = 3$ , $b = - 10$ , and $c = - 7$ into the quadratic formula and solve for $x$ .

$\frac{10 \pm \sqrt{{(- 10)}^{2} - 4 \cdot (3 \cdot - 7)}}{2 \cdot 3}$

Step 2.3

Simplify.

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Step 2.3.1

Simplify the numerator.

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Step 2.3.1.1

Raise $- 10$ to the power of $2$ .

$x = \frac{10 \pm \sqrt{100 - 4 \cdot 3 \cdot - 7}}{2 \cdot 3}$

Step 2.3.1.2

Multiply $- 4 \cdot 3 \cdot - 7$ .

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Step 2.3.1.2.1

Multiply $- 4$ by $3$ .

$x = \frac{10 \pm \sqrt{100 - 12 \cdot - 7}}{2 \cdot 3}$

Step 2.3.1.2.2

Multiply $- 12$ by $- 7$ .

$x = \frac{10 \pm \sqrt{100 + 84}}{2 \cdot 3}$

Step 2.3.1.3

Add $100$ and $84$ .

$x = \frac{10 \pm \sqrt{184}}{2 \cdot 3}$

Step 2.3.1.4

Rewrite $184$ as $2^{2} \cdot 46$ .

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Step 2.3.1.4.1

Factor $4$ out of $184$ .

$x = \frac{10 \pm \sqrt{4 (46)}}{2 \cdot 3}$

Step 2.3.1.4.2

Rewrite $4$ as $2^{2}$ .

$x = \frac{10 \pm \sqrt{2^{2} \cdot 46}}{2 \cdot 3}$

Step 2.3.1.5

Pull terms out from under the radical.

$x = \frac{10 \pm 2 \sqrt{46}}{2 \cdot 3}$

Step 2.3.2

Multiply $2$ by $3$ .

$x = \frac{10 \pm 2 \sqrt{46}}{6}$

Step 2.3.3

Simplify $\frac{10 \pm 2 \sqrt{46}}{6}$ .

$x = \frac{5 \pm \sqrt{46}}{3}$

Step 2.4

Simplify the expression to solve for the $+$ portion of the $\pm$ .

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Step 2.4.1

Simplify the numerator.

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Step 2.4.1.1

Raise $- 10$ to the power of $2$ .

$x = \frac{10 \pm \sqrt{100 - 4 \cdot 3 \cdot - 7}}{2 \cdot 3}$

Step 2.4.1.2

Multiply $- 4 \cdot 3 \cdot - 7$ .

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Step 2.4.1.2.1

Multiply $- 4$ by $3$ .

$x = \frac{10 \pm \sqrt{100 - 12 \cdot - 7}}{2 \cdot 3}$

Step 2.4.1.2.2

Multiply $- 12$ by $- 7$ .

$x = \frac{10 \pm \sqrt{100 + 84}}{2 \cdot 3}$

Step 2.4.1.3

Add $100$ and $84$ .

$x = \frac{10 \pm \sqrt{184}}{2 \cdot 3}$

Step 2.4.1.4

Rewrite $184$ as $2^{2} \cdot 46$ .

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Step 2.4.1.4.1

Factor $4$ out of $184$ .

$x = \frac{10 \pm \sqrt{4 (46)}}{2 \cdot 3}$

Step 2.4.1.4.2

Rewrite $4$ as $2^{2}$ .

$x = \frac{10 \pm \sqrt{2^{2} \cdot 46}}{2 \cdot 3}$

Step 2.4.1.5

Pull terms out from under the radical.

$x = \frac{10 \pm 2 \sqrt{46}}{2 \cdot 3}$

Step 2.4.2

Multiply $2$ by $3$ .

$x = \frac{10 \pm 2 \sqrt{46}}{6}$

Step 2.4.3

Simplify $\frac{10 \pm 2 \sqrt{46}}{6}$ .

$x = \frac{5 \pm \sqrt{46}}{3}$

Step 2.4.4

Change the $\pm$ to $+$ .

$x = \frac{5 + \sqrt{46}}{3}$

Step 2.5

Simplify the expression to solve for the $-$ portion of the $\pm$ .

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Step 2.5.1

Simplify the numerator.

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Step 2.5.1.1

Raise $- 10$ to the power of $2$ .

$x = \frac{10 \pm \sqrt{100 - 4 \cdot 3 \cdot - 7}}{2 \cdot 3}$

Step 2.5.1.2

Multiply $- 4 \cdot 3 \cdot - 7$ .

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Step 2.5.1.2.1

Multiply $- 4$ by $3$ .

$x = \frac{10 \pm \sqrt{100 - 12 \cdot - 7}}{2 \cdot 3}$

Step 2.5.1.2.2

Multiply $- 12$ by $- 7$ .

$x = \frac{10 \pm \sqrt{100 + 84}}{2 \cdot 3}$

Step 2.5.1.3

Add $100$ and $84$ .

$x = \frac{10 \pm \sqrt{184}}{2 \cdot 3}$

Step 2.5.1.4

Rewrite $184$ as $2^{2} \cdot 46$ .

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Step 2.5.1.4.1

Factor $4$ out of $184$ .

$x = \frac{10 \pm \sqrt{4 (46)}}{2 \cdot 3}$

Step 2.5.1.4.2

Rewrite $4$ as $2^{2}$ .

$x = \frac{10 \pm \sqrt{2^{2} \cdot 46}}{2 \cdot 3}$

Step 2.5.1.5

Pull terms out from under the radical.

$x = \frac{10 \pm 2 \sqrt{46}}{2 \cdot 3}$

Step 2.5.2

Multiply $2$ by $3$ .

$x = \frac{10 \pm 2 \sqrt{46}}{6}$

Step 2.5.3

Simplify $\frac{10 \pm 2 \sqrt{46}}{6}$ .

$x = \frac{5 \pm \sqrt{46}}{3}$

Step 2.5.4

Change the $\pm$ to $-$ .

$x = \frac{5 - \sqrt{46}}{3}$

Step 2.6

The final answer is the combination of both solutions.

$x = \frac{5 + \sqrt{46}}{3}, \frac{5 - \sqrt{46}}{3}$

Step 3

Solve the original function $f (x) = x^{3} - 5 x^{2} - 7 x + 9$ at $x = \frac{5 + \sqrt{46}}{3}$ .

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Step 3.1

Replace the variable $x$ with $\frac{5 + \sqrt{46}}{3}$ in the expression.

$f (\frac{5 + \sqrt{46}}{3}) = {(\frac{5 + \sqrt{46}}{3})}^{3} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2

Simplify the result.

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Step 3.2.1

Simplify each term.

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Step 3.2.1.1

Apply the product rule to $\frac{5 + \sqrt{46}}{3}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{{(5 + \sqrt{46})}^{3}}{3^{3}} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.2

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

$f (\frac{5 + \sqrt{46}}{3}) = \frac{{(5 + \sqrt{46})}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.3

Use the Binomial Theorem.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{5^{3} + 3 \cdot (5^{2} \sqrt{46}) + 3 \cdot (5 {\sqrt{46}}^{2}) + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4

Simplify each term.

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Step 3.2.1.4.1

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

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 3 \cdot (5^{2} \sqrt{46}) + 3 \cdot (5 {\sqrt{46}}^{2}) + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.2

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

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 3 \cdot (25 \sqrt{46}) + 3 \cdot (5 {\sqrt{46}}^{2}) + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.3

Multiply $3$ by $25$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 3 \cdot (5 {\sqrt{46}}^{2}) + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.4

Multiply $3$ by $5$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 15 {\sqrt{46}}^{2} + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.5

Rewrite ${\sqrt{46}}^{2}$ as $46$ .

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Step 3.2.1.4.5.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{46}$ as $46^{\frac{1}{2}}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 15 {(46^{\frac{1}{2}})}^{2} + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.5.2

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

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 15 \cdot 46^{\frac{1}{2} \cdot 2} + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.5.3

Combine $\frac{1}{2}$ and $2$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 15 \cdot 46^{\frac{2}{2}} + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.5.4

Cancel the common factor of $2$ .

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Step 3.2.1.4.5.4.1

Cancel the common factor.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 15 \cdot 46^{\frac{2}{2}} + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.5.4.2

Rewrite the expression.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 15 \cdot 46 + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.5.5

Evaluate the exponent.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 15 \cdot 46 + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.6

Multiply $15$ by $46$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 690 + {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.7

Rewrite ${\sqrt{46}}^{3}$ as $\sqrt{46^{3}}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 690 + \sqrt{46^{3}}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.8

Raise $46$ to the power of $3$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 690 + \sqrt{97336}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.9

Rewrite $97336$ as $46^{2} \cdot 46$ .

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Step 3.2.1.4.9.1

Factor $2116$ out of $97336$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 690 + \sqrt{2116 (46)}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.9.2

Rewrite $2116$ as $46^{2}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 690 + \sqrt{46^{2} \cdot 46}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.4.10

Pull terms out from under the radical.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{125 + 75 \sqrt{46} + 690 + 46 \sqrt{46}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.5

Add $125$ and $690$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 75 \sqrt{46} + 46 \sqrt{46}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.6

Add $75 \sqrt{46}$ and $46 \sqrt{46}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 {(\frac{5 + \sqrt{46}}{3})}^{2} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.7

Apply the product rule to $\frac{5 + \sqrt{46}}{3}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{{(5 + \sqrt{46})}^{2}}{3^{2}} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.8

Raise $3$ to the power of $2$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{{(5 + \sqrt{46})}^{2}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.9

Rewrite ${(5 + \sqrt{46})}^{2}$ as $(5 + \sqrt{46}) (5 + \sqrt{46})$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{(5 + \sqrt{46}) (5 + \sqrt{46})}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.10

Expand $(5 + \sqrt{46}) (5 + \sqrt{46})$ using the FOIL Method.

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Step 3.2.1.10.1

Apply the distributive property.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{5 (5 + \sqrt{46}) + \sqrt{46} (5 + \sqrt{46})}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.10.2

Apply the distributive property.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{5 \cdot 5 + 5 \sqrt{46} + \sqrt{46} (5 + \sqrt{46})}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.10.3

Apply the distributive property.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{5 \cdot 5 + 5 \sqrt{46} + \sqrt{46} \cdot 5 + \sqrt{46} \sqrt{46}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.11

Simplify and combine like terms.

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Step 3.2.1.11.1

Simplify each term.

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Step 3.2.1.11.1.1

Multiply $5$ by $5$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{25 + 5 \sqrt{46} + \sqrt{46} \cdot 5 + \sqrt{46} \sqrt{46}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.11.1.2

Move $5$ to the left of $\sqrt{46}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{25 + 5 \sqrt{46} + 5 \cdot \sqrt{46} + \sqrt{46} \sqrt{46}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.11.1.3

Combine using the product rule for radicals.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{25 + 5 \sqrt{46} + 5 \sqrt{46} + \sqrt{46 \cdot 46}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.11.1.4

Multiply $46$ by $46$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{25 + 5 \sqrt{46} + 5 \sqrt{46} + \sqrt{2116}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.11.1.5

Rewrite $2116$ as $46^{2}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{25 + 5 \sqrt{46} + 5 \sqrt{46} + \sqrt{46^{2}}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.11.1.6

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

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{25 + 5 \sqrt{46} + 5 \sqrt{46} + 46}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.11.2

Add $25$ and $46$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{71 + 5 \sqrt{46} + 5 \sqrt{46}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.11.3

Add $5 \sqrt{46}$ and $5 \sqrt{46}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - 5 \frac{71 + 10 \sqrt{46}}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.12

Combine $- 5$ and $\frac{71 + 10 \sqrt{46}}{9}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} + \frac{- 5 (71 + 10 \sqrt{46})}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.13

Move the negative in front of the fraction.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46})}{9} - 7 \frac{5 + \sqrt{46}}{3} + 9$

Step 3.2.1.14

Combine $- 7$ and $\frac{5 + \sqrt{46}}{3}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46})}{9} + \frac{- 7 (5 + \sqrt{46})}{3} + 9$

Step 3.2.1.15

Move the negative in front of the fraction.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46})}{9} - \frac{7 (5 + \sqrt{46})}{3} + 9$

Step 3.2.2

Find the common denominator.

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Step 3.2.2.1

Multiply $\frac{5 (71 + 10 \sqrt{46})}{9}$ by $\frac{3}{3}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - (\frac{5 (71 + 10 \sqrt{46})}{9} \cdot \frac{3}{3}) - \frac{7 (5 + \sqrt{46})}{3} + 9$

Step 3.2.2.2

Multiply $\frac{5 (71 + 10 \sqrt{46})}{9}$ by $\frac{3}{3}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 + \sqrt{46})}{3} + 9$

Step 3.2.2.3

Multiply $\frac{7 (5 + \sqrt{46})}{3}$ by $\frac{9}{9}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - (\frac{7 (5 + \sqrt{46})}{3} \cdot \frac{9}{9}) + 9$

Step 3.2.2.4

Multiply $\frac{7 (5 + \sqrt{46})}{3}$ by $\frac{9}{9}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 + \sqrt{46}) \cdot 9}{3 \cdot 9} + 9$

Step 3.2.2.5

Write $9$ as a fraction with denominator $1$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 + \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9}{1}$

Step 3.2.2.6

Multiply $\frac{9}{1}$ by $\frac{27}{27}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 + \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9}{1} \cdot \frac{27}{27}$

Step 3.2.2.7

Multiply $\frac{9}{1}$ by $\frac{27}{27}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 + \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9 \cdot 27}{27}$

Step 3.2.2.8

Reorder the factors of $9 \cdot 3$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{3 \cdot 9} - \frac{7 (5 + \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9 \cdot 27}{27}$

Step 3.2.2.9

Multiply $3$ by $9$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{27} - \frac{7 (5 + \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9 \cdot 27}{27}$

Step 3.2.2.10

Multiply $3$ by $9$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46}}{27} - \frac{5 (71 + 10 \sqrt{46}) \cdot 3}{27} - \frac{7 (5 + \sqrt{46}) \cdot 9}{27} + \frac{9 \cdot 27}{27}$

Step 3.2.3

Combine the numerators over the common denominator.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 5 (71 + 10 \sqrt{46}) \cdot 3 - 7 (5 + \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4

Simplify each term.

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Step 3.2.4.1

Apply the distributive property.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} + (- 5 \cdot 71 - 5 (10 \sqrt{46})) \cdot 3 - 7 (5 + \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.2

Multiply $- 5$ by $71$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} + (- 355 - 5 (10 \sqrt{46})) \cdot 3 - 7 (5 + \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.3

Multiply $10$ by $- 5$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} + (- 355 - 50 \sqrt{46}) \cdot 3 - 7 (5 + \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.4

Apply the distributive property.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 355 \cdot 3 - 50 \sqrt{46} \cdot 3 - 7 (5 + \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.5

Multiply $- 355$ by $3$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 1065 - 50 \sqrt{46} \cdot 3 - 7 (5 + \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.6

Multiply $3$ by $- 50$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 1065 - 150 \sqrt{46} - 7 (5 + \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.7

Apply the distributive property.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 1065 - 150 \sqrt{46} + (- 7 \cdot 5 - 7 \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.8

Multiply $- 7$ by $5$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 1065 - 150 \sqrt{46} + (- 35 - 7 \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.9

Apply the distributive property.

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 1065 - 150 \sqrt{46} - 35 \cdot 9 - 7 \sqrt{46} \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.10

Multiply $- 35$ by $9$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 1065 - 150 \sqrt{46} - 315 - 7 \sqrt{46} \cdot 9 + 9 \cdot 27}{27}$

Step 3.2.4.11

Multiply $9$ by $- 7$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 1065 - 150 \sqrt{46} - 315 - 63 \sqrt{46} + 9 \cdot 27}{27}$

Step 3.2.4.12

Multiply $9$ by $27$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{815 + 121 \sqrt{46} - 1065 - 150 \sqrt{46} - 315 - 63 \sqrt{46} + 243}{27}$

Step 3.2.5

Simplify terms.

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Step 3.2.5.1

Subtract $1065$ from $815$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{- 250 + 121 \sqrt{46} - 150 \sqrt{46} - 315 - 63 \sqrt{46} + 243}{27}$

Step 3.2.5.2

Simplify by adding and subtracting.

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Step 3.2.5.2.1

Subtract $315$ from $- 250$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{- 565 + 121 \sqrt{46} - 150 \sqrt{46} - 63 \sqrt{46} + 243}{27}$

Step 3.2.5.2.2

Add $- 565$ and $243$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{- 322 + 121 \sqrt{46} - 150 \sqrt{46} - 63 \sqrt{46}}{27}$

Step 3.2.5.3

Subtract $150 \sqrt{46}$ from $121 \sqrt{46}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{- 322 - 29 \sqrt{46} - 63 \sqrt{46}}{27}$

Step 3.2.5.4

Subtract $63 \sqrt{46}$ from $- 29 \sqrt{46}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{- 322 - 92 \sqrt{46}}{27}$

Step 3.2.5.5

Rewrite $- 322$ as $- 1 (322)$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{- 1 \cdot 322 - 92 \sqrt{46}}{27}$

Step 3.2.5.6

Factor $- 1$ out of $- 92 \sqrt{46}$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{- 1 \cdot 322 - (92 \sqrt{46})}{27}$

Step 3.2.5.7

Factor $- 1$ out of $- 1 (322) - (92 \sqrt{46})$ .

$f (\frac{5 + \sqrt{46}}{3}) = \frac{- 1 (322 + 92 \sqrt{46})}{27}$

Step 3.2.5.8

Move the negative in front of the fraction.

$f (\frac{5 + \sqrt{46}}{3}) = - \frac{322 + 92 \sqrt{46}}{27}$

Step 3.2.6

The final answer is $- \frac{322 + 92 \sqrt{46}}{27}$ .

$- \frac{322 + 92 \sqrt{46}}{27}$

Step 4

Solve the original function $f (x) = x^{3} - 5 x^{2} - 7 x + 9$ at $x = \frac{5 - \sqrt{46}}{3}$ .

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Step 4.1

Replace the variable $x$ with $\frac{5 - \sqrt{46}}{3}$ in the expression.

$f (\frac{5 - \sqrt{46}}{3}) = {(\frac{5 - \sqrt{46}}{3})}^{3} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2

Simplify the result.

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Step 4.2.1

Simplify each term.

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Step 4.2.1.1

Apply the product rule to $\frac{5 - \sqrt{46}}{3}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{{(5 - \sqrt{46})}^{3}}{3^{3}} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.2

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

$f (\frac{5 - \sqrt{46}}{3}) = \frac{{(5 - \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.3

Use the Binomial Theorem.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{5^{3} + 3 \cdot (5^{2} (- \sqrt{46})) + 3 \cdot (5 {(- \sqrt{46})}^{2}) + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4

Simplify each term.

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Step 4.2.1.4.1

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

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 + 3 \cdot (5^{2} (- \sqrt{46})) + 3 \cdot (5 {(- \sqrt{46})}^{2}) + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.2

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

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 + 3 \cdot (25 (- \sqrt{46})) + 3 \cdot (5 {(- \sqrt{46})}^{2}) + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.3

Multiply $3$ by $25$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 + 75 (- \sqrt{46}) + 3 \cdot (5 {(- \sqrt{46})}^{2}) + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.4

Multiply $- 1$ by $75$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 3 \cdot (5 {(- \sqrt{46})}^{2}) + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.5

Multiply $3$ by $5$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 {(- \sqrt{46})}^{2} + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.6

Apply the product rule to $- \sqrt{46}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 ({(- 1)}^{2} {\sqrt{46}}^{2}) + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.7

Raise $- 1$ to the power of $2$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 (1 {\sqrt{46}}^{2}) + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.8

Multiply ${\sqrt{46}}^{2}$ by $1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 {\sqrt{46}}^{2} + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.9

Rewrite ${\sqrt{46}}^{2}$ as $46$ .

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Step 4.2.1.4.9.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{46}$ as $46^{\frac{1}{2}}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 {(46^{\frac{1}{2}})}^{2} + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.9.2

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

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 \cdot 46^{\frac{1}{2} \cdot 2} + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.9.3

Combine $\frac{1}{2}$ and $2$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 \cdot 46^{\frac{2}{2}} + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.9.4

Cancel the common factor of $2$ .

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Step 4.2.1.4.9.4.1

Cancel the common factor.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 \cdot 46^{\frac{2}{2}} + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.9.4.2

Rewrite the expression.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 \cdot 46 + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.9.5

Evaluate the exponent.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 15 \cdot 46 + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.10

Multiply $15$ by $46$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 + {(- \sqrt{46})}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.11

Apply the product rule to $- \sqrt{46}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 + {(- 1)}^{3} {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.12

Raise $- 1$ to the power of $3$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 - {\sqrt{46}}^{3}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.13

Rewrite ${\sqrt{46}}^{3}$ as $\sqrt{46^{3}}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 - \sqrt{46^{3}}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.14

Raise $46$ to the power of $3$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 - \sqrt{97336}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.15

Rewrite $97336$ as $46^{2} \cdot 46$ .

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Step 4.2.1.4.15.1

Factor $2116$ out of $97336$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 - \sqrt{2116 (46)}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.15.2

Rewrite $2116$ as $46^{2}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 - \sqrt{46^{2} \cdot 46}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.16

Pull terms out from under the radical.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 - (46 \sqrt{46})}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.4.17

Multiply $46$ by $- 1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{125 - 75 \sqrt{46} + 690 - 46 \sqrt{46}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.5

Add $125$ and $690$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 75 \sqrt{46} - 46 \sqrt{46}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.6

Subtract $46 \sqrt{46}$ from $- 75 \sqrt{46}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 {(\frac{5 - \sqrt{46}}{3})}^{2} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.7

Apply the product rule to $\frac{5 - \sqrt{46}}{3}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{{(5 - \sqrt{46})}^{2}}{3^{2}} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.8

Raise $3$ to the power of $2$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{{(5 - \sqrt{46})}^{2}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.9

Rewrite ${(5 - \sqrt{46})}^{2}$ as $(5 - \sqrt{46}) (5 - \sqrt{46})$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{(5 - \sqrt{46}) (5 - \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.10

Expand $(5 - \sqrt{46}) (5 - \sqrt{46})$ using the FOIL Method.

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Step 4.2.1.10.1

Apply the distributive property.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{5 (5 - \sqrt{46}) - \sqrt{46} (5 - \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.10.2

Apply the distributive property.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{5 \cdot 5 + 5 (- \sqrt{46}) - \sqrt{46} (5 - \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.10.3

Apply the distributive property.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{5 \cdot 5 + 5 (- \sqrt{46}) - \sqrt{46} \cdot 5 - \sqrt{46} (- \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11

Simplify and combine like terms.

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Step 4.2.1.11.1

Simplify each term.

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Step 4.2.1.11.1.1

Multiply $5$ by $5$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 + 5 (- \sqrt{46}) - \sqrt{46} \cdot 5 - \sqrt{46} (- \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.2

Multiply $- 1$ by $5$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - \sqrt{46} \cdot 5 - \sqrt{46} (- \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.3

Multiply $5$ by $- 1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} - \sqrt{46} (- \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.4

Multiply $- \sqrt{46} (- \sqrt{46})$ .

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Step 4.2.1.11.1.4.1

Multiply $- 1$ by $- 1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + 1 \sqrt{46} \sqrt{46}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.4.2

Multiply $\sqrt{46}$ by $1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + \sqrt{46} \sqrt{46}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.4.3

Raise $\sqrt{46}$ to the power of $1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + \sqrt{46} \sqrt{46}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.4.4

Raise $\sqrt{46}$ to the power of $1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + \sqrt{46} \sqrt{46}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.4.5

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

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + {\sqrt{46}}^{1 + 1}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.4.6

Add $1$ and $1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + {\sqrt{46}}^{2}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.5

Rewrite ${\sqrt{46}}^{2}$ as $46$ .

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Step 4.2.1.11.1.5.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{46}$ as $46^{\frac{1}{2}}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + {(46^{\frac{1}{2}})}^{2}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.5.2

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

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + 46^{\frac{1}{2} \cdot 2}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.5.3

Combine $\frac{1}{2}$ and $2$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + 46^{\frac{2}{2}}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.5.4

Cancel the common factor of $2$ .

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Step 4.2.1.11.1.5.4.1

Cancel the common factor.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + 46^{\frac{2}{2}}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.5.4.2

Rewrite the expression.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + 46}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.1.5.5

Evaluate the exponent.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{25 - 5 \sqrt{46} - 5 \sqrt{46} + 46}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.2

Add $25$ and $46$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{71 - 5 \sqrt{46} - 5 \sqrt{46}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.11.3

Subtract $5 \sqrt{46}$ from $- 5 \sqrt{46}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - 5 \frac{71 - 10 \sqrt{46}}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.12

Combine $- 5$ and $\frac{71 - 10 \sqrt{46}}{9}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} + \frac{- 5 (71 - 10 \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.13

Move the negative in front of the fraction.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46})}{9} - 7 \frac{5 - \sqrt{46}}{3} + 9$

Step 4.2.1.14

Combine $- 7$ and $\frac{5 - \sqrt{46}}{3}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46})}{9} + \frac{- 7 (5 - \sqrt{46})}{3} + 9$

Step 4.2.1.15

Move the negative in front of the fraction.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46})}{9} - \frac{7 (5 - \sqrt{46})}{3} + 9$

Step 4.2.2

Find the common denominator.

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Step 4.2.2.1

Multiply $\frac{5 (71 - 10 \sqrt{46})}{9}$ by $\frac{3}{3}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - (\frac{5 (71 - 10 \sqrt{46})}{9} \cdot \frac{3}{3}) - \frac{7 (5 - \sqrt{46})}{3} + 9$

Step 4.2.2.2

Multiply $\frac{5 (71 - 10 \sqrt{46})}{9}$ by $\frac{3}{3}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 - \sqrt{46})}{3} + 9$

Step 4.2.2.3

Multiply $\frac{7 (5 - \sqrt{46})}{3}$ by $\frac{9}{9}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - (\frac{7 (5 - \sqrt{46})}{3} \cdot \frac{9}{9}) + 9$

Step 4.2.2.4

Multiply $\frac{7 (5 - \sqrt{46})}{3}$ by $\frac{9}{9}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 - \sqrt{46}) \cdot 9}{3 \cdot 9} + 9$

Step 4.2.2.5

Write $9$ as a fraction with denominator $1$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 - \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9}{1}$

Step 4.2.2.6

Multiply $\frac{9}{1}$ by $\frac{27}{27}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 - \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9}{1} \cdot \frac{27}{27}$

Step 4.2.2.7

Multiply $\frac{9}{1}$ by $\frac{27}{27}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{9 \cdot 3} - \frac{7 (5 - \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9 \cdot 27}{27}$

Step 4.2.2.8

Reorder the factors of $9 \cdot 3$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{3 \cdot 9} - \frac{7 (5 - \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9 \cdot 27}{27}$

Step 4.2.2.9

Multiply $3$ by $9$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{27} - \frac{7 (5 - \sqrt{46}) \cdot 9}{3 \cdot 9} + \frac{9 \cdot 27}{27}$

Step 4.2.2.10

Multiply $3$ by $9$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46}}{27} - \frac{5 (71 - 10 \sqrt{46}) \cdot 3}{27} - \frac{7 (5 - \sqrt{46}) \cdot 9}{27} + \frac{9 \cdot 27}{27}$

Step 4.2.3

Combine the numerators over the common denominator.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 5 (71 - 10 \sqrt{46}) \cdot 3 - 7 (5 - \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4

Simplify each term.

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Step 4.2.4.1

Apply the distributive property.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} + (- 5 \cdot 71 - 5 (- 10 \sqrt{46})) \cdot 3 - 7 (5 - \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.2

Multiply $- 5$ by $71$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} + (- 355 - 5 (- 10 \sqrt{46})) \cdot 3 - 7 (5 - \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.3

Multiply $- 10$ by $- 5$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} + (- 355 + 50 \sqrt{46}) \cdot 3 - 7 (5 - \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.4

Apply the distributive property.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 355 \cdot 3 + 50 \sqrt{46} \cdot 3 - 7 (5 - \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.5

Multiply $- 355$ by $3$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 50 \sqrt{46} \cdot 3 - 7 (5 - \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.6

Multiply $3$ by $50$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 150 \sqrt{46} - 7 (5 - \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.7

Apply the distributive property.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 150 \sqrt{46} + (- 7 \cdot 5 - 7 (- \sqrt{46})) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.8

Multiply $- 7$ by $5$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 150 \sqrt{46} + (- 35 - 7 (- \sqrt{46})) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.9

Multiply $- 1$ by $- 7$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 150 \sqrt{46} + (- 35 + 7 \sqrt{46}) \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.10

Apply the distributive property.

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 150 \sqrt{46} - 35 \cdot 9 + 7 \sqrt{46} \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.11

Multiply $- 35$ by $9$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 150 \sqrt{46} - 315 + 7 \sqrt{46} \cdot 9 + 9 \cdot 27}{27}$

Step 4.2.4.12

Multiply $9$ by $7$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 150 \sqrt{46} - 315 + 63 \sqrt{46} + 9 \cdot 27}{27}$

Step 4.2.4.13

Multiply $9$ by $27$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{815 - 121 \sqrt{46} - 1065 + 150 \sqrt{46} - 315 + 63 \sqrt{46} + 243}{27}$

Step 4.2.5

Simplify terms.

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Step 4.2.5.1

Subtract $1065$ from $815$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{- 250 - 121 \sqrt{46} + 150 \sqrt{46} - 315 + 63 \sqrt{46} + 243}{27}$

Step 4.2.5.2

Simplify by adding and subtracting.

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Step 4.2.5.2.1

Subtract $315$ from $- 250$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{- 565 - 121 \sqrt{46} + 150 \sqrt{46} + 63 \sqrt{46} + 243}{27}$

Step 4.2.5.2.2

Add $- 565$ and $243$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{- 322 - 121 \sqrt{46} + 150 \sqrt{46} + 63 \sqrt{46}}{27}$

Step 4.2.5.3

Add $- 121 \sqrt{46}$ and $150 \sqrt{46}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{- 322 + 29 \sqrt{46} + 63 \sqrt{46}}{27}$

Step 4.2.5.4

Add $29 \sqrt{46}$ and $63 \sqrt{46}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{- 322 + 92 \sqrt{46}}{27}$

Step 4.2.5.5

Rewrite $- 322$ as $- 1 (322)$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{- 1 \cdot 322 + 92 \sqrt{46}}{27}$

Step 4.2.5.6

Factor $- 1$ out of $92 \sqrt{46}$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{- 1 \cdot 322 - (- 92 \sqrt{46})}{27}$

Step 4.2.5.7

Factor $- 1$ out of $- 1 (322) - (- 92 \sqrt{46})$ .

$f (\frac{5 - \sqrt{46}}{3}) = \frac{- 1 (322 - 92 \sqrt{46})}{27}$

Step 4.2.5.8

Move the negative in front of the fraction.

$f (\frac{5 - \sqrt{46}}{3}) = - \frac{322 - 92 \sqrt{46}}{27}$

Step 4.2.6

The final answer is $- \frac{322 - 92 \sqrt{46}}{27}$ .

$- \frac{322 - 92 \sqrt{46}}{27}$

Step 5

The horizontal tangent lines on function $f (x) = x^{3} - 5 x^{2} - 7 x + 9$ are $y = - \frac{322 + 92 \sqrt{46}}{27}, y = - \frac{322 - 92 \sqrt{46}}{27}$ .

$y = - \frac{322 + 92 \sqrt{46}}{27}, y = - \frac{322 - 92 \sqrt{46}}{27}$

Step 6