Precalculus Examples

$\log (\sqrt{\frac{x^{2} + 7}{(x^{4} + 8) {(x^{2} - 16)}^{5}}})$

Step 1

Rewrite $16$ as $4^{2}$ .

$\log (\sqrt{\frac{x^{2} + 7}{(x^{4} + 8) {(x^{2} - 4^{2})}^{5}}})$

Step 2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = x$ and $b = 4$ .

$\log (\sqrt{\frac{x^{2} + 7}{(x^{4} + 8) {((x + 4) (x - 4))}^{5}}})$

Step 3

Apply the product rule to $(x + 4) (x - 4)$ .

$\log (\sqrt{\frac{x^{2} + 7}{(x^{4} + 8) {(x + 4)}^{5} {(x - 4)}^{5}}})$

Step 4

Rewrite $\frac{x^{2} + 7}{(x^{4} + 8) {(x + 4)}^{5} {(x - 4)}^{5}}$ as ${(\frac{1}{{(x + 4)}^{2} {(x - 4)}^{2}})}^{2} \frac{x^{2} + 7}{(x^{4} + 8) (x + 4) (x - 4)}$ .

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Step 4.1

Factor the perfect power $1^{2}$ out of $x^{2} + 7$ .

$\log (\sqrt{\frac{1^{2} (x^{2} + 7)}{(x^{4} + 8) {(x + 4)}^{5} {(x - 4)}^{5}}})$

Step 4.2

Rearrange the fraction $\frac{1^{2} (x^{2} + 7)}{{({(x + 4)}^{2} {(x - 4)}^{2})}^{2} ((x^{4} + 8) (x + 4) (x - 4))}$ .

$\log (\sqrt{{(\frac{1}{{(x + 4)}^{2} {(x - 4)}^{2}})}^{2} \frac{x^{2} + 7}{(x^{4} + 8) (x + 4) (x - 4)}})$

Step 5

Pull terms out from under the radical.

$\log (\frac{1}{{(x + 4)}^{2} {(x - 4)}^{2}} \sqrt{\frac{x^{2} + 7}{(x^{4} + 8) (x + 4) (x - 4)}})$

Step 6

Rewrite $\sqrt{\frac{x^{2} + 7}{(x^{4} + 8) (x + 4) (x - 4)}}$ as $\frac{\sqrt{x^{2} + 7}}{\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}$ .

$\log (\frac{1}{{(x + 4)}^{2} {(x - 4)}^{2}} \cdot \frac{\sqrt{x^{2} + 7}}{\sqrt{(x^{4} + 8) (x + 4) (x - 4)}})$

Step 7

Combine.

$\log (\frac{1 \sqrt{x^{2} + 7}}{{(x + 4)}^{2} {(x - 4)}^{2} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}})$

Step 8

Multiply $\sqrt{x^{2} + 7}$ by $1$ .

$\log (\frac{\sqrt{x^{2} + 7}}{{(x + 4)}^{2} {(x - 4)}^{2} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}})$

Step 9

Multiply $\frac{\sqrt{x^{2} + 7}}{{(x + 4)}^{2} {(x - 4)}^{2} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}$ by $\frac{\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}$ .

$\log (\frac{\sqrt{x^{2} + 7}}{{(x + 4)}^{2} {(x - 4)}^{2} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}} \cdot \frac{\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{\sqrt{(x^{4} + 8) (x + 4) (x - 4)}})$

Step 10

Combine and simplify the denominator.

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Step 10.1

Multiply $\frac{\sqrt{x^{2} + 7}}{{(x + 4)}^{2} {(x - 4)}^{2} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}$ by $\frac{\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} \sqrt{(x^{4} + 8) (x + 4) (x - 4)} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}})$

Step 10.2

Move $\sqrt{(x^{4} + 8) (x + 4) (x - 4)}$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} (\sqrt{(x^{4} + 8) (x + 4) (x - 4)} \sqrt{(x^{4} + 8) (x + 4) (x - 4)})})$

Step 10.3

Raise $\sqrt{(x^{4} + 8) (x + 4) (x - 4)}$ to the power of $1$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} ({\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}^{1} \sqrt{(x^{4} + 8) (x + 4) (x - 4)})})$

Step 10.4

Raise $\sqrt{(x^{4} + 8) (x + 4) (x - 4)}$ to the power of $1$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} ({\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}^{1} {\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}^{1})})$

Step 10.5

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

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} {\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}^{1 + 1}})$

Step 10.6

Add $1$ and $1$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} {\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}^{2}})$

Step 10.7

Rewrite ${\sqrt{(x^{4} + 8) (x + 4) (x - 4)}}^{2}$ as $(x^{4} + 8) (x + 4) (x - 4)$ .

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Step 10.7.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{(x^{4} + 8) (x + 4) (x - 4)}$ as ${((x^{4} + 8) (x + 4) (x - 4))}^{\frac{1}{2}}$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} {({((x^{4} + 8) (x + 4) (x - 4))}^{\frac{1}{2}})}^{2}})$

Step 10.7.2

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

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} {((x^{4} + 8) (x + 4) (x - 4))}^{\frac{1}{2} \cdot 2}})$

Step 10.7.3

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

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} {((x^{4} + 8) (x + 4) (x - 4))}^{\frac{2}{2}}})$

Step 10.7.4

Cancel the common factor of $2$ .

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Step 10.7.4.1

Cancel the common factor.

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} {((x^{4} + 8) (x + 4) (x - 4))}^{\frac{2}{2}}})$

Step 10.7.4.2

Rewrite the expression.

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} {((x^{4} + 8) (x + 4) (x - 4))}^{1}})$

Step 10.7.5

Simplify.

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{2} {(x - 4)}^{2} ((x^{4} + 8) (x + 4) (x - 4))})$

Step 11

Multiply ${(x + 4)}^{2}$ by $x + 4$ by adding the exponents.

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Step 11.1

Move $x + 4$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{(x + 4) {(x + 4)}^{2} {(x - 4)}^{2} ((x^{4} + 8) (x - 4))})$

Step 11.2

Multiply $x + 4$ by ${(x + 4)}^{2}$ .

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Step 11.2.1

Raise $x + 4$ to the power of $1$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{1} {(x + 4)}^{2} {(x - 4)}^{2} ((x^{4} + 8) (x - 4))})$

Step 11.2.2

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

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{1 + 2} {(x - 4)}^{2} ((x^{4} + 8) (x - 4))})$

Step 11.3

Add $1$ and $2$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{3} {(x - 4)}^{2} ((x^{4} + 8) (x - 4))})$

Step 12

Multiply ${(x - 4)}^{2}$ by $x - 4$ by adding the exponents.

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Step 12.1

Move $x - 4$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{3} ((x - 4) {(x - 4)}^{2}) (x^{4} + 8)})$

Step 12.2

Multiply $x - 4$ by ${(x - 4)}^{2}$ .

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Step 12.2.1

Raise $x - 4$ to the power of $1$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{3} ({(x - 4)}^{1} {(x - 4)}^{2}) (x^{4} + 8)})$

Step 12.2.2

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

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{3} {(x - 4)}^{1 + 2} (x^{4} + 8)})$

Step 12.3

Add $1$ and $2$ .

$\log (\frac{\sqrt{x^{2} + 7} \sqrt{(x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{3} {(x - 4)}^{3} (x^{4} + 8)})$

Step 13

Combine using the product rule for radicals.

$\log (\frac{\sqrt{(x^{2} + 7) (x^{4} + 8) (x + 4) (x - 4)}}{{(x + 4)}^{3} {(x - 4)}^{3} (x^{4} + 8)})$