Algebra Examples

$\frac{x - 2}{x^{2} + 2 x + 4} - \frac{6 x}{x^{3} - 8} + \frac{1}{x - 2}$

Step 1

Simplify the denominator.

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Step 1.1

Rewrite $8$ as $2^{3}$ .

$\frac{x - 2}{x^{2} + 2 x + 4} - \frac{6 x}{x^{3} - 2^{3}} + \frac{1}{x - 2}$

Step 1.2

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

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

Step 1.3

Simplify.

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Step 1.3.1

Move $2$ to the left of $x$ .

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

Step 1.3.2

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

$\frac{x - 2}{x^{2} + 2 x + 4} - \frac{6 x}{(x - 2) (x^{2} + 2 x + 4)} + \frac{1}{x - 2}$

Step 2

To write $\frac{x - 2}{x^{2} + 2 x + 4}$ as a fraction with a common denominator, multiply by $\frac{x - 2}{x - 2}$ .

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

Step 3

Write each expression with a common denominator of $(x^{2} + 2 x + 4) (x - 2)$ , by multiplying each by an appropriate factor of $1$ .

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Step 3.1

Multiply $\frac{x - 2}{x^{2} + 2 x + 4}$ by $\frac{x - 2}{x - 2}$ .

$\frac{(x - 2) (x - 2)}{(x^{2} + 2 x + 4) (x - 2)} - \frac{6 x}{(x - 2) (x^{2} + 2 x + 4)} + \frac{1}{x - 2}$

Step 3.2

Reorder the factors of $(x^{2} + 2 x + 4) (x - 2)$ .

$\frac{(x - 2) (x - 2)}{(x - 2) (x^{2} + 2 x + 4)} - \frac{6 x}{(x - 2) (x^{2} + 2 x + 4)} + \frac{1}{x - 2}$

Step 4

Combine the numerators over the common denominator.

$\frac{(x - 2) (x - 2) - 6 x}{(x - 2) (x^{2} + 2 x + 4)} + \frac{1}{x - 2}$

Step 5

Simplify the numerator.

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Step 5.1

Expand $(x - 2) (x - 2)$ using the FOIL Method.

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Step 5.1.1

Apply the distributive property.

$\frac{x (x - 2) - 2 (x - 2) - 6 x}{(x - 2) (x^{2} + 2 x + 4)} + \frac{1}{x - 2}$

Step 5.1.2

Apply the distributive property.

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

Step 5.1.3

Apply the distributive property.

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

Step 5.2

Simplify and combine like terms.

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Step 5.2.1

Simplify each term.

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Step 5.2.1.1

Multiply $x$ by $x$ .

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

Step 5.2.1.2

Move $- 2$ to the left of $x$ .

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

Step 5.2.1.3

Multiply $- 2$ by $- 2$ .

$\frac{x^{2} - 2 x - 2 x + 4 - 6 x}{(x - 2) (x^{2} + 2 x + 4)} + \frac{1}{x - 2}$

Step 5.2.2

Subtract $2 x$ from $- 2 x$ .

$\frac{x^{2} - 4 x + 4 - 6 x}{(x - 2) (x^{2} + 2 x + 4)} + \frac{1}{x - 2}$

Step 5.3

Subtract $6 x$ from $- 4 x$ .

$\frac{x^{2} - 10 x + 4}{(x - 2) (x^{2} + 2 x + 4)} + \frac{1}{x - 2}$

Step 6

To write $\frac{1}{x - 2}$ as a fraction with a common denominator, multiply by $\frac{x^{2} + 2 x + 4}{x^{2} + 2 x + 4}$ .

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

Step 7

Simplify terms.

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Step 7.1

Multiply $\frac{1}{x - 2}$ by $\frac{x^{2} + 2 x + 4}{x^{2} + 2 x + 4}$ .

$\frac{x^{2} - 10 x + 4}{(x - 2) (x^{2} + 2 x + 4)} + \frac{x^{2} + 2 x + 4}{(x - 2) (x^{2} + 2 x + 4)}$

Step 7.2

Combine the numerators over the common denominator.

$\frac{x^{2} - 10 x + 4 + x^{2} + 2 x + 4}{(x - 2) (x^{2} + 2 x + 4)}$

Step 8

Simplify the numerator.

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Step 8.1

Add $x^{2}$ and $x^{2}$ .

$\frac{2 x^{2} - 10 x + 4 + 2 x + 4}{(x - 2) (x^{2} + 2 x + 4)}$

Step 8.2

Add $- 10 x$ and $2 x$ .

$\frac{2 x^{2} - 8 x + 4 + 4}{(x - 2) (x^{2} + 2 x + 4)}$

Step 8.3

Add $4$ and $4$ .

$\frac{2 x^{2} - 8 x + 8}{(x - 2) (x^{2} + 2 x + 4)}$

Step 8.4

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

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Step 8.4.1

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

$\frac{2 (x^{2}) - 8 x + 8}{(x - 2) (x^{2} + 2 x + 4)}$

Step 8.4.2

Factor $2$ out of $- 8 x$ .

$\frac{2 (x^{2}) + 2 (- 4 x) + 8}{(x - 2) (x^{2} + 2 x + 4)}$

Step 8.4.3

Factor $2$ out of $8$ .

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

Step 8.4.4

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

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

Step 8.4.5

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

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

Step 8.5

Factor using the perfect square rule.

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Step 8.5.1

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

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

Step 8.5.2

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

$4 x = 2 \cdot x \cdot 2$

Step 8.5.3

Rewrite the polynomial.

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

Step 8.5.4

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

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

Step 9

Cancel the common factor of ${(x - 2)}^{2}$ and $x - 2$ .

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Step 9.1

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

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

Step 9.2

Cancel the common factors.

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Step 9.2.1

Cancel the common factor.

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

Step 9.2.2

Rewrite the expression.

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