Algebra Examples

$\frac{x^{2} - 14 x + 48}{x^{2} - x - 2} \cdot \frac{16 - 4 x^{2}}{x^{2} - 4 x - 12} \div \frac{x^{2} + x - 72}{x^{2} + 10 x + 9}$

Step 1

To divide by a fraction, multiply by its reciprocal.

$\frac{x^{2} - 14 x + 48}{x^{2} - x - 2} \cdot \frac{16 - 4 x^{2}}{x^{2} - 4 x - 12} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 2

Factor $x^{2} - 14 x + 48$ using the AC method.

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Step 2.1

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 $48$ and whose sum is $- 14$ .

$- 8, - 6$

Step 2.2

Write the factored form using these integers.

$\frac{(x - 8) (x - 6)}{x^{2} - x - 2} \cdot \frac{16 - 4 x^{2}}{x^{2} - 4 x - 12} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 3

Factor $x^{2} - x - 2$ 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 $- 2$ and whose sum is $- 1$ .

$- 2, 1$

Step 3.2

Write the factored form using these integers.

$\frac{(x - 8) (x - 6)}{(x - 2) (x + 1)} \cdot \frac{16 - 4 x^{2}}{x^{2} - 4 x - 12} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 4

Simplify the numerator.

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Step 4.1

Factor $4$ out of $16 - 4 x^{2}$ .

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Step 4.1.1

Factor $4$ out of $16$ .

$\frac{(x - 8) (x - 6)}{(x - 2) (x + 1)} \cdot \frac{4 (4) - 4 x^{2}}{x^{2} - 4 x - 12} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 4.1.2

Factor $4$ out of $- 4 x^{2}$ .

$\frac{(x - 8) (x - 6)}{(x - 2) (x + 1)} \cdot \frac{4 (4) + 4 (- x^{2})}{x^{2} - 4 x - 12} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 4.1.3

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

$\frac{(x - 8) (x - 6)}{(x - 2) (x + 1)} \cdot \frac{4 (4 - x^{2})}{x^{2} - 4 x - 12} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 4.2

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

$\frac{(x - 8) (x - 6)}{(x - 2) (x + 1)} \cdot \frac{4 (2^{2} - x^{2})}{x^{2} - 4 x - 12} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

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 $a = 2$ and $b = x$ .

$\frac{(x - 8) (x - 6)}{(x - 2) (x + 1)} \cdot \frac{4 (2 + x) (2 - x)}{x^{2} - 4 x - 12} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 5

Factor $x^{2} - 4 x - 12$ using the AC method.

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Step 5.1

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 $- 12$ and whose sum is $- 4$ .

$- 6, 2$

Step 5.2

Write the factored form using these integers.

$\frac{(x - 8) (x - 6)}{(x - 2) (x + 1)} \cdot \frac{4 (2 + x) (2 - x)}{(x - 6) (x + 2)} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6

Simplify terms.

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Step 6.1

Cancel the common factor of $x - 6$ .

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Step 6.1.1

Factor $x - 6$ out of $(x - 8) (x - 6)$ .

$\frac{(x - 6) (x - 8)}{(x - 2) (x + 1)} \cdot \frac{4 (2 + x) (2 - x)}{(x - 6) (x + 2)} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.1.2

Cancel the common factor.

$\frac{(x - 6) (x - 8)}{(x - 2) (x + 1)} \cdot \frac{4 (2 + x) (2 - x)}{(x - 6) (x + 2)} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.1.3

Rewrite the expression.

$\frac{x - 8}{(x - 2) (x + 1)} \cdot \frac{4 (2 + x) (2 - x)}{x + 2} \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.2

Multiply $\frac{x - 8}{(x - 2) (x + 1)}$ by $\frac{4 (2 + x) (2 - x)}{x + 2}$ .

$\frac{(x - 8) (4 (2 + x) (2 - x))}{(x - 2) (x + 1) (x + 2)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.3

Cancel the common factor of $2 + x$ and $x + 2$ .

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Step 6.3.1

Reorder terms.

$\frac{(x - 8) (4 (x + 2) (2 - x))}{(x - 2) (x + 1) (x + 2)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.3.2

Cancel the common factor.

$\frac{(x - 8) (4 (x + 2) (2 - x))}{(x - 2) (x + 1) (x + 2)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.3.3

Rewrite the expression.

$\frac{(x - 8) (4 (2 - x))}{(x - 2) (x + 1)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.4

Cancel the common factor of $2 - x$ and $x - 2$ .

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Step 6.4.1

Rewrite $2$ as $- 1 (- 2)$ .

$\frac{(x - 8) (4 (- 1 (- 2) - x))}{(x - 2) (x + 1)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.4.2

Factor $- 1$ out of $- x$ .

$\frac{(x - 8) (4 (- 1 (- 2) - (x)))}{(x - 2) (x + 1)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.4.3

Factor $- 1$ out of $- 1 (- 2) - (x)$ .

$\frac{(x - 8) (4 (- 1 (- 2 + x)))}{(x - 2) (x + 1)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.4.4

Reorder terms.

$\frac{(x - 8) \cdot 4 (- 1 (x - 2))}{(x - 2) (x + 1)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.4.5

Cancel the common factor.

$\frac{(x - 8) \cdot 4 (- 1 (x - 2))}{(x - 2) (x + 1)} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.4.6

Rewrite the expression.

$\frac{(x - 8) \cdot 4 \cdot (- 1)}{x + 1} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.5

Simplify the expression.

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Step 6.5.1

Multiply $- 1$ by $4$ .

$\frac{(x - 8) \cdot - 4}{x + 1} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.5.2

Move $- 4$ to the left of $x - 8$ .

$\frac{- 4 \cdot (x - 8)}{x + 1} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 6.5.3

Move the negative in front of the fraction.

$- \frac{4 \cdot (x - 8)}{x + 1} \cdot \frac{x^{2} + 10 x + 9}{x^{2} + x - 72}$

Step 7

Factor $x^{2} + 10 x + 9$ using the AC method.

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Step 7.1

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 $9$ and whose sum is $10$ .

$1, 9$

Step 7.2

Write the factored form using these integers.

$- \frac{4 (x - 8)}{x + 1} \cdot \frac{(x + 1) (x + 9)}{x^{2} + x - 72}$

Step 8

Factor $x^{2} + x - 72$ using the AC method.

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Step 8.1

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 $- 72$ and whose sum is $1$ .

$- 8, 9$

Step 8.2

Write the factored form using these integers.

$- \frac{4 (x - 8)}{x + 1} \cdot \frac{(x + 1) (x + 9)}{(x - 8) (x + 9)}$

Step 9

Simplify terms.

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Step 9.1

Cancel the common factor of $x - 8$ .

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Step 9.1.1

Move the leading negative in $- \frac{4 (x - 8)}{x + 1}$ into the numerator.

$\frac{- 4 (x - 8)}{x + 1} \cdot \frac{(x + 1) (x + 9)}{(x - 8) (x + 9)}$

Step 9.1.2

Factor $x - 8$ out of $- 4 (x - 8)$ .

$\frac{(x - 8) \cdot - 4}{x + 1} \cdot \frac{(x + 1) (x + 9)}{(x - 8) (x + 9)}$

Step 9.1.3

Cancel the common factor.

$\frac{(x - 8) \cdot - 4}{x + 1} \cdot \frac{(x + 1) (x + 9)}{(x - 8) (x + 9)}$

Step 9.1.4

Rewrite the expression.

$\frac{- 4}{x + 1} \cdot \frac{(x + 1) (x + 9)}{x + 9}$

Step 9.2

Cancel the common factor of $x + 1$ .

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Step 9.2.1

Cancel the common factor.

$\frac{- 4}{x + 1} \cdot \frac{(x + 1) (x + 9)}{x + 9}$

Step 9.2.2

Rewrite the expression.

$- 4 \frac{x + 9}{x + 9}$

Step 9.3

Combine $- 4$ and $\frac{x + 9}{x + 9}$ .

$\frac{- 4 (x + 9)}{x + 9}$

Step 9.4

Cancel the common factor of $x + 9$ .

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Step 9.4.1

Cancel the common factor.

$\frac{- 4 (x + 9)}{x + 9}$

Step 9.4.2

Divide $- 4$ by $1$ .

$- 4$