Finite Math Examples

$\frac{x}{x - 2} - \frac{7}{x + 2} = \frac{8}{x^{2} - 4}$

Step 1

Simplify $\frac{x}{x - 2} - \frac{7}{x + 2}$ .

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Step 1.1

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

$\frac{x}{x - 2} \cdot \frac{x + 2}{x + 2} - \frac{7}{x + 2} = \frac{8}{x^{2} - 4}$

Step 1.2

To write $- \frac{7}{x + 2}$ as a fraction with a common denominator, multiply by $\frac{x - 2}{x - 2}$ .

$\frac{x}{x - 2} \cdot \frac{x + 2}{x + 2} - \frac{7}{x + 2} \cdot \frac{x - 2}{x - 2} = \frac{8}{x^{2} - 4}$

Step 1.3

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

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Step 1.3.1

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

$\frac{x (x + 2)}{(x - 2) (x + 2)} - \frac{7}{x + 2} \cdot \frac{x - 2}{x - 2} = \frac{8}{x^{2} - 4}$

Step 1.3.2

Multiply $\frac{7}{x + 2}$ by $\frac{x - 2}{x - 2}$ .

$\frac{x (x + 2)}{(x - 2) (x + 2)} - \frac{7 (x - 2)}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 1.3.3

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

$\frac{x (x + 2)}{(x + 2) (x - 2)} - \frac{7 (x - 2)}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 1.4

Combine the numerators over the common denominator.

$\frac{x (x + 2) - 7 (x - 2)}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 1.5

Simplify the numerator.

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Step 1.5.1

Apply the distributive property.

$\frac{x \cdot x + x \cdot 2 - 7 (x - 2)}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 1.5.2

Multiply $x$ by $x$ .

$\frac{x^{2} + x \cdot 2 - 7 (x - 2)}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 1.5.3

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

$\frac{x^{2} + 2 \cdot x - 7 (x - 2)}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 1.5.4

Apply the distributive property.

$\frac{x^{2} + 2 x - 7 x - 7 \cdot - 2}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 1.5.5

Multiply $- 7$ by $- 2$ .

$\frac{x^{2} + 2 x - 7 x + 14}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 1.5.6

Subtract $7 x$ from $2 x$ .

$\frac{x^{2} - 5 x + 14}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 4}$

Step 2

Simplify the denominator.

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Step 2.1

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

$\frac{x^{2} - 5 x + 14}{(x + 2) (x - 2)} = \frac{8}{x^{2} - 2^{2}}$

Step 2.2

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

$\frac{x^{2} - 5 x + 14}{(x + 2) (x - 2)} = \frac{8}{(x + 2) (x - 2)}$

Step 3

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

$x = 3$

Step 4