Algebra Examples

$s (x) = x^{2} + 2 x - 4$ $w (x) = \frac{4}{x - 9}$

Step 1

Set up the composite result function.

$s (w (x))$

Step 2

Evaluate $s (\frac{4}{x - 9})$ by substituting in the value of $w$ into $s$ .

$s (\frac{4}{x - 9}) = {(\frac{4}{x - 9})}^{2} + 2 (\frac{4}{x - 9}) - 4$

Step 3

Simplify each term.

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Step 3.1

Apply the product rule to $\frac{4}{x - 9}$ .

$s (\frac{4}{x - 9}) = \frac{4^{2}}{{(x - 9)}^{2}} + 2 (\frac{4}{x - 9}) - 4$

Step 3.2

Raise $4$ to the power of $2$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + 2 (\frac{4}{x - 9}) - 4$

Step 3.3

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

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Step 3.3.1

Combine $2$ and $\frac{4}{x - 9}$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{2 \cdot 4}{x - 9} - 4$

Step 3.3.2

Multiply $2$ by $4$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8}{x - 9} - 4$

Step 4

Find the common denominator.

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Step 4.1

Multiply $\frac{8}{x - 9}$ by $\frac{x - 9}{x - 9}$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8}{x - 9} \cdot \frac{x - 9}{x - 9} - 4$

Step 4.2

Multiply $\frac{8}{x - 9}$ by $\frac{x - 9}{x - 9}$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8 (x - 9)}{(x - 9) (x - 9)} - 4$

Step 4.3

Write $- 4$ as a fraction with denominator $1$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8 (x - 9)}{(x - 9) (x - 9)} + \frac{- 4}{1}$

Step 4.4

Multiply $\frac{- 4}{1}$ by $\frac{{(x - 9)}^{2}}{{(x - 9)}^{2}}$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8 (x - 9)}{(x - 9) (x - 9)} + \frac{- 4}{1} \cdot \frac{{(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 4.5

Multiply $\frac{- 4}{1}$ by $\frac{{(x - 9)}^{2}}{{(x - 9)}^{2}}$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8 (x - 9)}{(x - 9) (x - 9)} + \frac{- 4 {(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 4.6

Raise $x - 9$ to the power of $1$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8 (x - 9)}{(x - 9) (x - 9)} + \frac{- 4 {(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 4.7

Raise $x - 9$ to the power of $1$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8 (x - 9)}{(x - 9) (x - 9)} + \frac{- 4 {(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 4.8

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

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8 (x - 9)}{{(x - 9)}^{1 + 1}} + \frac{- 4 {(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 4.9

Add $1$ and $1$ .

$s (\frac{4}{x - 9}) = \frac{16}{{(x - 9)}^{2}} + \frac{8 (x - 9)}{{(x - 9)}^{2}} + \frac{- 4 {(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 5

Combine the numerators over the common denominator.

$s (\frac{4}{x - 9}) = \frac{16 + 8 (x - 9) - 4 {(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 6

Simplify each term.

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Step 6.1

Apply the distributive property.

$s (\frac{4}{x - 9}) = \frac{16 + 8 x + 8 \cdot - 9 - 4 {(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 6.2

Multiply $8$ by $- 9$ .

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 {(x - 9)}^{2}}{{(x - 9)}^{2}}$

Step 6.3

Rewrite ${(x - 9)}^{2}$ as $(x - 9) (x - 9)$ .

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 ((x - 9) (x - 9))}{{(x - 9)}^{2}}$

Step 6.4

Expand $(x - 9) (x - 9)$ using the FOIL Method.

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Step 6.4.1

Apply the distributive property.

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 (x (x - 9) - 9 (x - 9))}{{(x - 9)}^{2}}$

Step 6.4.2

Apply the distributive property.

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 (x \cdot x + x \cdot - 9 - 9 (x - 9))}{{(x - 9)}^{2}}$

Step 6.4.3

Apply the distributive property.

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 (x \cdot x + x \cdot - 9 - 9 x - 9 \cdot - 9)}{{(x - 9)}^{2}}$

Step 6.5

Simplify and combine like terms.

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Step 6.5.1

Simplify each term.

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Step 6.5.1.1

Multiply $x$ by $x$ .

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 (x^{2} + x \cdot - 9 - 9 x - 9 \cdot - 9)}{{(x - 9)}^{2}}$

Step 6.5.1.2

Move $- 9$ to the left of $x$ .

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 (x^{2} - 9 \cdot x - 9 x - 9 \cdot - 9)}{{(x - 9)}^{2}}$

Step 6.5.1.3

Multiply $- 9$ by $- 9$ .

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 (x^{2} - 9 x - 9 x + 81)}{{(x - 9)}^{2}}$

Step 6.5.2

Subtract $9 x$ from $- 9 x$ .

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 (x^{2} - 18 x + 81)}{{(x - 9)}^{2}}$

Step 6.6

Apply the distributive property.

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 x^{2} - 4 (- 18 x) - 4 \cdot 81}{{(x - 9)}^{2}}$

Step 6.7

Simplify.

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Step 6.7.1

Multiply $- 18$ by $- 4$ .

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 x^{2} + 72 x - 4 \cdot 81}{{(x - 9)}^{2}}$

Step 6.7.2

Multiply $- 4$ by $81$ .

$s (\frac{4}{x - 9}) = \frac{16 + 8 x - 72 - 4 x^{2} + 72 x - 324}{{(x - 9)}^{2}}$

Step 7

Simplify terms.

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Step 7.1

Subtract $72$ from $16$ .

$s (\frac{4}{x - 9}) = \frac{8 x - 56 - 4 x^{2} + 72 x - 324}{{(x - 9)}^{2}}$

Step 7.2

Add $8 x$ and $72 x$ .

$s (\frac{4}{x - 9}) = \frac{80 x - 56 - 4 x^{2} - 324}{{(x - 9)}^{2}}$

Step 7.3

Simplify the expression.

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Step 7.3.1

Subtract $324$ from $- 56$ .

$s (\frac{4}{x - 9}) = \frac{80 x - 4 x^{2} - 380}{{(x - 9)}^{2}}$

Step 7.3.2

Reorder $80 x$ and $- 4 x^{2}$ .

$s (\frac{4}{x - 9}) = \frac{- 4 x^{2} + 80 x - 380}{{(x - 9)}^{2}}$

Step 7.4

Factor $4$ out of $- 4 x^{2} + 80 x - 380$ .

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Step 7.4.1

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

$s (\frac{4}{x - 9}) = \frac{4 (- x^{2}) + 80 x - 380}{{(x - 9)}^{2}}$

Step 7.4.2

Factor $4$ out of $80 x$ .

$s (\frac{4}{x - 9}) = \frac{4 (- x^{2}) + 4 (20 x) - 380}{{(x - 9)}^{2}}$

Step 7.4.3

Factor $4$ out of $- 380$ .

$s (\frac{4}{x - 9}) = \frac{4 (- x^{2}) + 4 (20 x) + 4 (- 95)}{{(x - 9)}^{2}}$

Step 7.4.4

Factor $4$ out of $4 (- x^{2}) + 4 (20 x)$ .

$s (\frac{4}{x - 9}) = \frac{4 (- x^{2} + 20 x) + 4 (- 95)}{{(x - 9)}^{2}}$

Step 7.4.5

Factor $4$ out of $4 (- x^{2} + 20 x) + 4 (- 95)$ .

$s (\frac{4}{x - 9}) = \frac{4 (- x^{2} + 20 x - 95)}{{(x - 9)}^{2}}$

Step 7.5

Factor $- 1$ out of $- x^{2}$ .

$s (\frac{4}{x - 9}) = \frac{4 (- (x^{2}) + 20 x - 95)}{{(x - 9)}^{2}}$

Step 7.6

Factor $- 1$ out of $20 x$ .

$s (\frac{4}{x - 9}) = \frac{4 (- (x^{2}) - (- 20 x) - 95)}{{(x - 9)}^{2}}$

Step 7.7

Factor $- 1$ out of $- (x^{2}) - (- 20 x)$ .

$s (\frac{4}{x - 9}) = \frac{4 (- (x^{2} - 20 x) - 95)}{{(x - 9)}^{2}}$

Step 7.8

Rewrite $- 95$ as $- 1 (95)$ .

$s (\frac{4}{x - 9}) = \frac{4 (- (x^{2} - 20 x) - 1 \cdot 95)}{{(x - 9)}^{2}}$

Step 7.9

Factor $- 1$ out of $- (x^{2} - 20 x) - 1 (95)$ .

$s (\frac{4}{x - 9}) = \frac{4 (- (x^{2} - 20 x + 95))}{{(x - 9)}^{2}}$

Step 7.10

Simplify the expression.

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Step 7.10.1

Rewrite $- (x^{2} - 20 x + 95)$ as $- 1 (x^{2} - 20 x + 95)$ .

$s (\frac{4}{x - 9}) = \frac{4 (- 1 (x^{2} - 20 x + 95))}{{(x - 9)}^{2}}$

Step 7.10.2

Move the negative in front of the fraction.

$s (\frac{4}{x - 9}) = - \frac{4 (x^{2} - 20 x + 95)}{{(x - 9)}^{2}}$