Algebra Examples

$\frac{2 x}{x^{2} + 6 x + 9} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x^{3} + 9 x^{2} + 18 x}{x + 6}$

Step 1

Simplify the numerator.

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Step 1.1

Factor $x$ out of $x^{3} + 9 x^{2} + 18 x$ .

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Step 1.1.1

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

$\frac{2 x}{x^{2} + 6 x + 9} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x \cdot x^{2} + 9 x^{2} + 18 x}{x + 6}$

Step 1.1.2

Factor $x$ out of $9 x^{2}$ .

$\frac{2 x}{x^{2} + 6 x + 9} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x \cdot x^{2} + x (9 x) + 18 x}{x + 6}$

Step 1.1.3

Factor $x$ out of $18 x$ .

$\frac{2 x}{x^{2} + 6 x + 9} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x \cdot x^{2} + x (9 x) + x \cdot 18}{x + 6}$

Step 1.1.4

Factor $x$ out of $x \cdot x^{2} + x (9 x)$ .

$\frac{2 x}{x^{2} + 6 x + 9} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x (x^{2} + 9 x) + x \cdot 18}{x + 6}$

Step 1.1.5

Factor $x$ out of $x (x^{2} + 9 x) + x \cdot 18$ .

$\frac{2 x}{x^{2} + 6 x + 9} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x (x^{2} + 9 x + 18)}{x + 6}$

Step 1.2

Factor $x^{2} + 9 x + 18$ using the AC method.

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Step 1.2.1

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 $18$ and whose sum is $9$ .

$3, 6$

Step 1.2.2

Write the factored form using these integers.

$\frac{2 x}{x^{2} + 6 x + 9} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x ((x + 3) (x + 6))}{x + 6}$

$\frac{2 x}{x^{2} + 6 x + 9} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 2

Factor using the perfect square rule.

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Step 2.1

Rewrite $9$ as $3^{2}$ .

$\frac{2 x}{x^{2} + 6 x + 3^{2}} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 2.2

Check that the middle term is two times the product of the numbers being squared in the first term and third term.

$6 x = 2 \cdot x \cdot 3$

Step 2.3

Rewrite the polynomial.

$\frac{2 x}{x^{2} + 2 \cdot x \cdot 3 + 3^{2}} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 2.4

Factor using the perfect square trinomial rule $a^{2} + 2 a b + b^{2} = {(a + b)}^{2}$ , where $a = x$ and $b = 3$ .

$\frac{2 x}{{(x + 3)}^{2}} \cdot \frac{4 x^{3} - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 3

Simplify the numerator.

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Step 3.1

Factor $4 x$ out of $4 x^{3} - 24 x^{2} - 108 x$ .

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Step 3.1.1

Factor $4 x$ out of $4 x^{3}$ .

$\frac{2 x}{{(x + 3)}^{2}} \cdot \frac{4 x (x^{2}) - 24 x^{2} - 108 x}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 3.1.2

Factor $4 x$ out of $- 24 x^{2}$ .

$\frac{2 x}{{(x + 3)}^{2}} \cdot \frac{4 x (x^{2}) + 4 x (- 6 x) - 108 x}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 3.1.3

Factor $4 x$ out of $- 108 x$ .

$\frac{2 x}{{(x + 3)}^{2}} \cdot \frac{4 x (x^{2}) + 4 x (- 6 x) + 4 x (- 27)}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 3.1.4

Factor $4 x$ out of $4 x (x^{2}) + 4 x (- 6 x)$ .

$\frac{2 x}{{(x + 3)}^{2}} \cdot \frac{4 x (x^{2} - 6 x) + 4 x (- 27)}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 3.1.5

Factor $4 x$ out of $4 x (x^{2} - 6 x) + 4 x (- 27)$ .

$\frac{2 x}{{(x + 3)}^{2}} \cdot \frac{4 x (x^{2} - 6 x - 27)}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 3.2

Factor $x^{2} - 6 x - 27$ using the AC method.

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Step 3.2.1

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 $- 27$ and whose sum is $- 6$ .

$- 9, 3$

Step 3.2.2

Write the factored form using these integers.

$\frac{2 x}{{(x + 3)}^{2}} \cdot \frac{4 x ((x - 9) (x + 3))}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

$\frac{2 x}{{(x + 3)}^{2}} \cdot \frac{4 x (x - 9) (x + 3)}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 4

Simplify terms.

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Step 4.1

Cancel the common factor of $x + 3$ .

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Step 4.1.1

Factor $x + 3$ out of ${(x + 3)}^{2}$ .

$\frac{2 x}{(x + 3) (x + 3)} \cdot \frac{4 x (x - 9) (x + 3)}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 4.1.2

Factor $x + 3$ out of $4 x (x - 9) (x + 3)$ .

$\frac{2 x}{(x + 3) (x + 3)} \cdot \frac{(x + 3) (4 x (x - 9))}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 4.1.3

Cancel the common factor.

$\frac{2 x}{(x + 3) (x + 3)} \cdot \frac{(x + 3) (4 x (x - 9))}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 4.1.4

Rewrite the expression.

$\frac{2 x}{x + 3} \cdot \frac{4 x (x - 9)}{x - 9} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 4.2

Multiply $\frac{2 x}{x + 3}$ by $\frac{4 x (x - 9)}{x - 9}$ .

$\frac{2 x (4 x (x - 9))}{(x + 3) (x - 9)} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 4.3

Multiply $4$ by $2$ .

$\frac{8 x (x (x - 9))}{(x + 3) (x - 9)} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 5

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

$\frac{8 (x^{1} x) (x - 9)}{(x + 3) (x - 9)} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 6

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

$\frac{8 (x^{1} x^{1}) (x - 9)}{(x + 3) (x - 9)} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 7

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

$\frac{8 x^{1 + 1} (x - 9)}{(x + 3) (x - 9)} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 8

Add $1$ and $1$ .

$\frac{8 x^{2} (x - 9)}{(x + 3) (x - 9)} \cdot \frac{x (x + 3) (x + 6)}{x + 6}$

Step 9

Cancel the common factor of $x + 3$ .

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Step 9.1

Factor $x + 3$ out of $x (x + 3) (x + 6)$ .

$\frac{8 x^{2} (x - 9)}{(x + 3) (x - 9)} \cdot \frac{(x + 3) (x (x + 6))}{x + 6}$

Step 9.2

Cancel the common factor.

$\frac{8 x^{2} (x - 9)}{(x + 3) (x - 9)} \cdot \frac{(x + 3) (x (x + 6))}{x + 6}$

Step 9.3

Rewrite the expression.

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

Step 10

Multiply $\frac{8 x^{2} (x - 9)}{x - 9}$ by $\frac{x (x + 6)}{x + 6}$ .

$\frac{8 x^{2} (x - 9) (x (x + 6))}{(x - 9) (x + 6)}$

Step 11

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

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

Step 12

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

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

Step 13

Add $1$ and $2$ .

$\frac{8 x^{3} (x - 9) (x + 6)}{(x - 9) (x + 6)}$

Step 14

Cancel the common factor of $x - 9$ .

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Step 14.1

Cancel the common factor.

$\frac{8 x^{3} (x - 9) (x + 6)}{(x - 9) (x + 6)}$

Step 14.2

Rewrite the expression.

$\frac{8 x^{3} (x + 6)}{x + 6}$

Step 15

Cancel the common factor of $x + 6$ .

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Step 15.1

Cancel the common factor.

$\frac{8 x^{3} (x + 6)}{x + 6}$

Step 15.2

Divide $8 x^{3}$ by $1$ .

$8 x^{3}$