Algebra Examples

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

Step 1

Simplify $\frac{x}{x + 4} + \frac{x - 1}{x + 2}$ .

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Step 1.1

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

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

Step 1.2

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

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

Step 1.3

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

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Step 1.3.1

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

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

Step 1.3.2

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

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

Step 1.3.3

Reorder the factors of $(x + 4) (x + 2)$ .

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

Step 1.4

Combine the numerators over the common denominator.

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

Step 1.5

Simplify the numerator.

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Step 1.5.1

Apply the distributive property.

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

Step 1.5.2

Multiply $x$ by $x$ .

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

Step 1.5.3

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

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

Step 1.5.4

Expand $(x - 1) (x + 4)$ using the FOIL Method.

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Step 1.5.4.1

Apply the distributive property.

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

Step 1.5.4.2

Apply the distributive property.

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

Step 1.5.4.3

Apply the distributive property.

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

Step 1.5.5

Simplify and combine like terms.

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Step 1.5.5.1

Simplify each term.

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Step 1.5.5.1.1

Multiply $x$ by $x$ .

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

Step 1.5.5.1.2

Move $4$ to the left of $x$ .

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

Step 1.5.5.1.3

Rewrite $- 1 x$ as $- x$ .

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

Step 1.5.5.1.4

Multiply $- 1$ by $4$ .

$\frac{x^{2} + 2 x + x^{2} + 4 x - x - 4}{(x + 2) (x + 4)} = \frac{3}{x^{2} + 2 x - 8}$

Step 1.5.5.2

Subtract $x$ from $4 x$ .

$\frac{x^{2} + 2 x + x^{2} + 3 x - 4}{(x + 2) (x + 4)} = \frac{3}{x^{2} + 2 x - 8}$

Step 1.5.6

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

$\frac{2 x^{2} + 2 x + 3 x - 4}{(x + 2) (x + 4)} = \frac{3}{x^{2} + 2 x - 8}$

Step 1.5.7

Add $2 x$ and $3 x$ .

$\frac{2 x^{2} + 5 x - 4}{(x + 2) (x + 4)} = \frac{3}{x^{2} + 2 x - 8}$

Step 2

Factor $x^{2} + 2 x - 8$ 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 $- 8$ and whose sum is $2$ .

$- 2, 4$

Step 2.2

Write the factored form using these integers.

$\frac{2 x^{2} + 5 x - 4}{(x + 2) (x + 4)} = \frac{3}{(x - 2) (x + 4)}$

Step 3

Graph each side of the equation. The solution is the x-value of the point of intersection.

$x \approx - 3.22862871, 0.11867209, 2.60995662$

Step 4