Algebra Examples

$\frac{9 x^{3} - 45 x^{2} + 36 x}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{9 - x^{2}}{x^{2} + 2 x - 3}$

Step 1

Simplify the numerator.

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Step 1.1

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

$\frac{9 x^{3} - 45 x^{2} + 36 x}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{3^{2} - x^{2}}{x^{2} + 2 x - 3}$

Step 1.2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 3$ and $b = x$ .

$\frac{9 x^{3} - 45 x^{2} + 36 x}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{x^{2} + 2 x - 3}$

Step 2

Factor $x^{2} + 2 x - 3$ 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 $- 3$ and whose sum is $2$ .

$- 1, 3$

Step 2.2

Write the factored form using these integers.

$\frac{9 x^{3} - 45 x^{2} + 36 x}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 3

Simplify the numerator.

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Step 3.1

Factor $9 x$ out of $9 x^{3} - 45 x^{2} + 36 x$ .

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Step 3.1.1

Factor $9 x$ out of $9 x^{3}$ .

$\frac{9 x (x^{2}) - 45 x^{2} + 36 x}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 3.1.2

Factor $9 x$ out of $- 45 x^{2}$ .

$\frac{9 x (x^{2}) + 9 x (- 5 x) + 36 x}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 3.1.3

Factor $9 x$ out of $36 x$ .

$\frac{9 x (x^{2}) + 9 x (- 5 x) + 9 x (4)}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 3.1.4

Factor $9 x$ out of $9 x (x^{2}) + 9 x (- 5 x)$ .

$\frac{9 x (x^{2} - 5 x) + 9 x (4)}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 3.1.5

Factor $9 x$ out of $9 x (x^{2} - 5 x) + 9 x (4)$ .

$\frac{9 x (x^{2} - 5 x + 4)}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 3.2

Factor $x^{2} - 5 x + 4$ 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 $4$ and whose sum is $- 5$ .

$- 4, - 1$

Step 3.2.2

Write the factored form using these integers.

$\frac{9 x ((x - 4) (x - 1))}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{x^{2} + 11 x + 18}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 4

Factor $x^{2} + 11 x + 18$ 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 $18$ and whose sum is $11$ .

$2, 9$

Step 4.2

Write the factored form using these integers.

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x^{3} - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 5

Simplify the denominator.

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Step 5.1

Factor $4 x$ out of $4 x^{3} - 8 x^{2} - 32 x$ .

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Step 5.1.1

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

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x (x^{2}) - 8 x^{2} - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 5.1.2

Factor $4 x$ out of $- 8 x^{2}$ .

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x (x^{2}) + 4 x (- 2 x) - 32 x} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 5.1.3

Factor $4 x$ out of $- 32 x$ .

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x (x^{2}) + 4 x (- 2 x) + 4 x (- 8)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 5.1.4

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

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x (x^{2} - 2 x) + 4 x (- 8)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 5.1.5

Factor $4 x$ out of $4 x (x^{2} - 2 x) + 4 x (- 8)$ .

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x (x^{2} - 2 x - 8)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 5.2

Factor $x^{2} - 2 x - 8$ using the AC method.

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Step 5.2.1

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 $- 8$ and whose sum is $- 2$ .

$- 4, 2$

Step 5.2.2

Write the factored form using these integers.

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x ((x - 4) (x + 2))} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

$\frac{9 x (x - 4) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x (x - 4) (x + 2)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6

Simplify terms.

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Step 6.1

Cancel the common factor of $x (x - 4)$ .

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Step 6.1.1

Factor $x (x - 4)$ out of $9 x (x - 4) (x - 1)$ .

$\frac{x (x - 4) ((9) (x - 1))}{x + 9} \cdot \frac{(x + 2) (x + 9)}{4 x (x - 4) (x + 2)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.1.2

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

$\frac{x (x - 4) ((9) (x - 1))}{x + 9} \cdot \frac{(x + 2) (x + 9)}{x (x - 4) ((4) (x + 2))} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.1.3

Cancel the common factor.

$\frac{x (x - 4) ((9) (x - 1))}{x + 9} \cdot \frac{(x + 2) (x + 9)}{x (x - 4) ((4) (x + 2))} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.1.4

Rewrite the expression.

$\frac{(9) (x - 1)}{x + 9} \cdot \frac{(x + 2) (x + 9)}{(4) (x + 2)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.2

Cancel the common factor of $x + 9$ .

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Step 6.2.1

Factor $x + 9$ out of $(x + 2) (x + 9)$ .

$\frac{(9) (x - 1)}{x + 9} \cdot \frac{(x + 9) (x + 2)}{(4) (x + 2)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.2.2

Cancel the common factor.

$\frac{(9) (x - 1)}{x + 9} \cdot \frac{(x + 9) (x + 2)}{(4) (x + 2)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.2.3

Rewrite the expression.

$(9) (x - 1) \cdot \frac{x + 2}{(4) (x + 2)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.3

Combine $\frac{x + 2}{(4) (x + 2)}$ and $9$ .

$\frac{(x + 2) \cdot 9}{(4) (x + 2)} (x - 1) \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.4

Cancel the common factor of $x - 1$ .

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Step 6.4.1

Factor $x - 1$ out of $\frac{(x + 2) \cdot 9}{(4) (x + 2)} (x - 1)$ .

$(x - 1) \frac{(x + 2) \cdot 9}{(4) (x + 2)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.4.2

Cancel the common factor.

$(x - 1) \frac{(x + 2) \cdot 9}{(4) (x + 2)} \cdot \frac{(3 + x) (3 - x)}{(x - 1) (x + 3)}$

Step 6.4.3

Rewrite the expression.

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

Step 6.5

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

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

Step 6.6

Cancel the common factor of $x + 2$ .

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Step 6.6.1

Cancel the common factor.

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

Step 6.6.2

Rewrite the expression.

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

Step 6.7

Cancel the common factor of $3 + x$ and $x + 3$ .

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Step 6.7.1

Reorder terms.

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

Step 6.7.2

Cancel the common factor.

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

Step 6.7.3

Rewrite the expression.

$\frac{9 (3 - x)}{4}$