Algebra Examples

$\frac{x^{2} + 15 x + 50}{- x^{2} - 10 x} \cdot \frac{x^{2} + 10 x + 16}{x^{2} + 7 x + 10} \div \frac{x^{3} + 13 x^{2} + 40 x}{25 - x^{2}}$

Step 1

To divide by a fraction, multiply by its reciprocal.

$\frac{x^{2} + 15 x + 50}{- x^{2} - 10 x} \cdot \frac{x^{2} + 10 x + 16}{x^{2} + 7 x + 10} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 2

Factor $x^{2} + 15 x + 50$ 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 $50$ and whose sum is $15$ .

$5, 10$

Step 2.2

Write the factored form using these integers.

$\frac{(x + 5) (x + 10)}{- x^{2} - 10 x} \cdot \frac{x^{2} + 10 x + 16}{x^{2} + 7 x + 10} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 3

Factor $x$ out of $- x^{2} - 10 x$ .

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Step 3.1

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

$\frac{(x + 5) (x + 10)}{x (- x) - 10 x} \cdot \frac{x^{2} + 10 x + 16}{x^{2} + 7 x + 10} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 3.2

Factor $x$ out of $- 10 x$ .

$\frac{(x + 5) (x + 10)}{x (- x) + x \cdot - 10} \cdot \frac{x^{2} + 10 x + 16}{x^{2} + 7 x + 10} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 3.3

Factor $x$ out of $x (- x) + x \cdot - 10$ .

$\frac{(x + 5) (x + 10)}{x (- x - 10)} \cdot \frac{x^{2} + 10 x + 16}{x^{2} + 7 x + 10} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 4

Factor $x^{2} + 10 x + 16$ using the AC method.

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Step 4.1

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 $16$ and whose sum is $10$ .

$2, 8$

Step 4.2

Write the factored form using these integers.

$\frac{(x + 5) (x + 10)}{x (- x - 10)} \cdot \frac{(x + 2) (x + 8)}{x^{2} + 7 x + 10} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 5

Factor $x^{2} + 7 x + 10$ 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 $10$ and whose sum is $7$ .

$2, 5$

Step 5.2

Write the factored form using these integers.

$\frac{(x + 5) (x + 10)}{x (- x - 10)} \cdot \frac{(x + 2) (x + 8)}{(x + 2) (x + 5)} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6

Simplify terms.

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Step 6.1

Cancel the common factor of $x + 5$ .

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Step 6.1.1

Factor $x + 5$ out of $(x + 2) (x + 5)$ .

$\frac{(x + 5) (x + 10)}{x (- x - 10)} \cdot \frac{(x + 2) (x + 8)}{(x + 5) (x + 2)} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.1.2

Cancel the common factor.

$\frac{(x + 5) (x + 10)}{x (- x - 10)} \cdot \frac{(x + 2) (x + 8)}{(x + 5) (x + 2)} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.1.3

Rewrite the expression.

$\frac{x + 10}{x (- x - 10)} \cdot \frac{(x + 2) (x + 8)}{x + 2} \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.2

Multiply $\frac{x + 10}{x (- x - 10)}$ by $\frac{(x + 2) (x + 8)}{x + 2}$ .

$\frac{(x + 10) ((x + 2) (x + 8))}{x (- x - 10) (x + 2)} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.3

Cancel the common factor of $x + 2$ .

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Step 6.3.1

Cancel the common factor.

$\frac{(x + 10) ((x + 2) (x + 8))}{x (- x - 10) (x + 2)} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.3.2

Rewrite the expression.

$\frac{(x + 10) (x + 8)}{x (- x - 10)} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.4

Cancel the common factor of $x + 10$ and $- x - 10$ .

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Step 6.4.1

Factor $- 1$ out of $x$ .

$\frac{(- 1 (- x) + 10) (x + 8)}{x (- x - 10)} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.4.2

Rewrite $10$ as $- 1 (- 10)$ .

$\frac{(- 1 (- x) - 1 (- 10)) (x + 8)}{x (- x - 10)} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.4.3

Factor $- 1$ out of $- 1 (- x) - 1 (- 10)$ .

$\frac{- 1 (- x - 10) (x + 8)}{x (- x - 10)} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.4.4

Cancel the common factor.

$\frac{- 1 (- x - 10) (x + 8)}{x (- x - 10)} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.4.5

Rewrite the expression.

$\frac{- 1 (x + 8)}{x} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 6.5

Move the negative in front of the fraction.

$- \frac{x + 8}{x} \cdot \frac{25 - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 7

Simplify the numerator.

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Step 7.1

Rewrite $25$ as $5^{2}$ .

$- \frac{x + 8}{x} \cdot \frac{5^{2} - x^{2}}{x^{3} + 13 x^{2} + 40 x}$

Step 7.2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 5$ and $b = x$ .

$- \frac{x + 8}{x} \cdot \frac{(5 + x) (5 - x)}{x^{3} + 13 x^{2} + 40 x}$

Step 8

Simplify the denominator.

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Step 8.1

Factor $x$ out of $x^{3} + 13 x^{2} + 40 x$ .

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Step 8.1.1

Factor $x$ out of $x^{3}$ .

$- \frac{x + 8}{x} \cdot \frac{(5 + x) (5 - x)}{x \cdot x^{2} + 13 x^{2} + 40 x}$

Step 8.1.2

Factor $x$ out of $13 x^{2}$ .

$- \frac{x + 8}{x} \cdot \frac{(5 + x) (5 - x)}{x \cdot x^{2} + x (13 x) + 40 x}$

Step 8.1.3

Factor $x$ out of $40 x$ .

$- \frac{x + 8}{x} \cdot \frac{(5 + x) (5 - x)}{x \cdot x^{2} + x (13 x) + x \cdot 40}$

Step 8.1.4

Factor $x$ out of $x \cdot x^{2} + x (13 x)$ .

$- \frac{x + 8}{x} \cdot \frac{(5 + x) (5 - x)}{x (x^{2} + 13 x) + x \cdot 40}$

Step 8.1.5

Factor $x$ out of $x (x^{2} + 13 x) + x \cdot 40$ .

$- \frac{x + 8}{x} \cdot \frac{(5 + x) (5 - x)}{x (x^{2} + 13 x + 40)}$

Step 8.2

Factor $x^{2} + 13 x + 40$ using the AC method.

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Step 8.2.1

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 $40$ and whose sum is $13$ .

$5, 8$

Step 8.2.2

Write the factored form using these integers.

$- \frac{x + 8}{x} \cdot \frac{(5 + x) (5 - x)}{x ((x + 5) (x + 8))}$

$- \frac{x + 8}{x} \cdot \frac{(5 + x) (5 - x)}{x (x + 5) (x + 8)}$

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 $- \frac{x + 8}{x}$ into the numerator.

$\frac{- (x + 8)}{x} \cdot \frac{(5 + x) (5 - x)}{x (x + 5) (x + 8)}$

Step 9.1.2

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

$\frac{(x + 8) \cdot - 1}{x} \cdot \frac{(5 + x) (5 - x)}{x (x + 5) (x + 8)}$

Step 9.1.3

Factor $x + 8$ out of $x (x + 5) (x + 8)$ .

$\frac{(x + 8) \cdot - 1}{x} \cdot \frac{(5 + x) (5 - x)}{(x + 8) (x (x + 5))}$

Step 9.1.4

Cancel the common factor.

$\frac{(x + 8) \cdot - 1}{x} \cdot \frac{(5 + x) (5 - x)}{(x + 8) (x (x + 5))}$

Step 9.1.5

Rewrite the expression.

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

Step 9.2

Multiply $\frac{- 1}{x}$ by $\frac{(5 + x) (5 - x)}{x (x + 5)}$ .

$\frac{- ((5 + x) (5 - x))}{x (x (x + 5))}$

Step 10

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

$\frac{- ((5 + x) (5 - x))}{x^{1} x (x + 5)}$

Step 11

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

$\frac{- ((5 + x) (5 - x))}{x^{1} x^{1} (x + 5)}$

Step 12

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

$\frac{- ((5 + x) (5 - x))}{x^{1 + 1} (x + 5)}$

Step 13

Add $1$ and $1$ .

$\frac{- ((5 + x) (5 - x))}{x^{2} (x + 5)}$

Step 14

Cancel the common factor of $5 + x$ and $x + 5$ .

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Step 14.1

Reorder terms.

$\frac{- ((x + 5) (5 - x))}{x^{2} (x + 5)}$

Step 14.2

Cancel the common factor.

$\frac{- ((x + 5) (5 - x))}{x^{2} (x + 5)}$

Step 14.3

Rewrite the expression.

$\frac{- (5 - x)}{x^{2}}$

Step 15

Move the negative in front of the fraction.

$- \frac{5 - x}{x^{2}}$