Basic Math Examples

$\frac{3 a^{2} + 12}{3 a^{2} - 15 a} \div \frac{a^{4} - 16}{a^{2} - 3 a - 10}$

Step 1

To divide by a fraction, multiply by its reciprocal.

$\frac{3 a^{2} + 12}{3 a^{2} - 15 a} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 2

Simplify terms.

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Step 2.1

Factor $3$ out of $3 a^{2} + 12$ .

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Step 2.1.1

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

$\frac{3 (a^{2}) + 12}{3 a^{2} - 15 a} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 2.1.2

Factor $3$ out of $12$ .

$\frac{3 a^{2} + 3 \cdot 4}{3 a^{2} - 15 a} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 2.1.3

Factor $3$ out of $3 a^{2} + 3 \cdot 4$ .

$\frac{3 (a^{2} + 4)}{3 a^{2} - 15 a} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 2.2

Factor $3 a$ out of $3 a^{2} - 15 a$ .

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Step 2.2.1

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

$\frac{3 (a^{2} + 4)}{3 a (a) - 15 a} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 2.2.2

Factor $3 a$ out of $- 15 a$ .

$\frac{3 (a^{2} + 4)}{3 a (a) + 3 a (- 5)} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 2.2.3

Factor $3 a$ out of $3 a (a) + 3 a (- 5)$ .

$\frac{3 (a^{2} + 4)}{3 a (a - 5)} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 2.3

Cancel the common factor of $3$ .

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Step 2.3.1

Cancel the common factor.

$\frac{3 (a^{2} + 4)}{3 a (a - 5)} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 2.3.2

Rewrite the expression.

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{a^{2} - 3 a - 10}{a^{4} - 16}$

Step 3

Factor $a^{2} - 3 a - 10$ using the AC method.

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Step 3.1

Consider the form $x^{2} + b x + c$ . Find a pair of integers whose product is $c$ and whose sum is $b$ . In this case, whose product is $- 10$ and whose sum is $- 3$ .

$- 5, 2$

Step 3.2

Write the factored form using these integers.

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{a^{4} - 16}$

Step 4

Simplify the denominator.

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Step 4.1

Rewrite $a^{4}$ as ${(a^{2})}^{2}$ .

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{{(a^{2})}^{2} - 16}$

Step 4.2

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

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{{(a^{2})}^{2} - 4^{2}}$

Step 4.3

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

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{(a^{2} + 4) (a^{2} - 4)}$

Step 4.4

Simplify.

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Step 4.4.1

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

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{(a^{2} + 4) (a^{2} - 2^{2})}$

Step 4.4.2

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

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{(a^{2} + 4) (a + 2) (a - 2)}$

Step 5

Simplify terms.

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Step 5.1

Cancel the common factor of $a^{2} + 4$ .

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Step 5.1.1

Factor $a^{2} + 4$ out of $(a^{2} + 4) (a + 2) (a - 2)$ .

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{(a^{2} + 4) ((a + 2) (a - 2))}$

Step 5.1.2

Cancel the common factor.

$\frac{a^{2} + 4}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{(a^{2} + 4) ((a + 2) (a - 2))}$

Step 5.1.3

Rewrite the expression.

$\frac{1}{a (a - 5)} \cdot \frac{(a - 5) (a + 2)}{(a + 2) (a - 2)}$

Step 5.2

Cancel the common factor of $a - 5$ .

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Step 5.2.1

Factor $a - 5$ out of $a (a - 5)$ .

$\frac{1}{(a - 5) a} \cdot \frac{(a - 5) (a + 2)}{(a + 2) (a - 2)}$

Step 5.2.2

Cancel the common factor.

$\frac{1}{(a - 5) a} \cdot \frac{(a - 5) (a + 2)}{(a + 2) (a - 2)}$

Step 5.2.3

Rewrite the expression.

$\frac{1}{a} \cdot \frac{a + 2}{(a + 2) (a - 2)}$

Step 5.3

Multiply $\frac{1}{a}$ by $\frac{a + 2}{(a + 2) (a - 2)}$ .

$\frac{a + 2}{a ((a + 2) (a - 2))}$

Step 5.4

Cancel the common factor of $a + 2$ .

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Step 5.4.1

Cancel the common factor.

$\frac{a + 2}{a ((a + 2) (a - 2))}$

Step 5.4.2

Rewrite the expression.

$\frac{1}{a (a - 2)}$