Algebra Examples

$\frac{1}{a + 2} + \frac{1}{a - 2} = \frac{4}{a^{2} - 4}$

Step 1

Factor each term.

Tap for more steps...

Step 1.1

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

$\frac{1}{a + 2} + \frac{1}{a - 2} = \frac{4}{a^{2} - 2^{2}}$

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 $a = a$ and $b = 2$ .

$\frac{1}{a + 2} + \frac{1}{a - 2} = \frac{4}{(a + 2) (a - 2)}$

Step 2

Find the LCD of the terms in the equation.

Tap for more steps...

Step 2.1

Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.

$a + 2, a - 2, (a + 2) (a - 2)$

Step 2.2

The LCM is the smallest positive number that all of the numbers divide into evenly.

1. List the prime factors of each number.

2. Multiply each factor the greatest number of times it occurs in either number.

Step 2.3

The number $1$ is not a prime number because it only has one positive factor, which is itself.

Not prime

Step 2.4

The LCM of $1, 1, 1$ is the result of multiplying all prime factors the greatest number of times they occur in either number.

$1$

Step 2.5

The factor for $a + 2$ is $a + 2$ itself.

$(a + 2) = a + 2$

$(a + 2)$ occurs $1$ time.

Step 2.6

The factor for $a - 2$ is $a - 2$ itself.

$(a - 2) = a - 2$

$(a - 2)$ occurs $1$ time.

Step 2.7

The factor for $a + 2$ is $a + 2$ itself.

$(a + 2) = a + 2$

$(a + 2)$ occurs $1$ time.

Step 2.8

The factor for $a - 2$ is $a - 2$ itself.

$(a - 2) = a - 2$

$(a - 2)$ occurs $1$ time.

Step 2.9

The LCM of $a + 2, a - 2, a + 2, a - 2$ is the result of multiplying all factors the greatest number of times they occur in either term.

$(a + 2) (a - 2)$

Step 3

Multiply each term in $\frac{1}{a + 2} + \frac{1}{a - 2} = \frac{4}{(a + 2) (a - 2)}$ by $(a + 2) (a - 2)$ to eliminate the fractions.

Tap for more steps...

Step 3.1

Multiply each term in $\frac{1}{a + 2} + \frac{1}{a - 2} = \frac{4}{(a + 2) (a - 2)}$ by $(a + 2) (a - 2)$ .

$\frac{1}{a + 2} ((a + 2) (a - 2)) + \frac{1}{a - 2} ((a + 2) (a - 2)) = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.2

Simplify the left side.

Tap for more steps...

Step 3.2.1

Simplify each term.

Tap for more steps...

Step 3.2.1.1

Cancel the common factor of $a + 2$ .

Tap for more steps...

Step 3.2.1.1.1

Cancel the common factor.

$\frac{1}{a + 2} ((a + 2) (a - 2)) + \frac{1}{a - 2} ((a + 2) (a - 2)) = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.2.1.1.2

Rewrite the expression.

$a - 2 + \frac{1}{a - 2} ((a + 2) (a - 2)) = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.2.1.2

Cancel the common factor of $a - 2$ .

Tap for more steps...

Step 3.2.1.2.1

Factor $a - 2$ out of $(a + 2) (a - 2)$ .

$a - 2 + \frac{1}{a - 2} ((a - 2) (a + 2)) = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.2.1.2.2

Cancel the common factor.

$a - 2 + \frac{1}{a - 2} ((a - 2) (a + 2)) = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.2.1.2.3

Rewrite the expression.

$a - 2 + a + 2 = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.2.2

Simplify by adding terms.

Tap for more steps...

Step 3.2.2.1

Combine the opposite terms in $a - 2 + a + 2$ .

Tap for more steps...

Step 3.2.2.1.1

Add $- 2$ and $2$ .

$a + a + 0 = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.2.2.1.2

Add $a + a$ and $0$ .

$a + a = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.2.2.2

Add $a$ and $a$ .

$2 a = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.3

Simplify the right side.

Tap for more steps...

Step 3.3.1

Cancel the common factor of $(a + 2) (a - 2)$ .

Tap for more steps...

Step 3.3.1.1

Cancel the common factor.

$2 a = \frac{4}{(a + 2) (a - 2)} ((a + 2) (a - 2))$

Step 3.3.1.2

Rewrite the expression.

$2 a = 4$

Step 4

Divide each term in $2 a = 4$ by $2$ and simplify.

Tap for more steps...

Step 4.1

Divide each term in $2 a = 4$ by $2$ .

$\frac{2 a}{2} = \frac{4}{2}$

Step 4.2

Simplify the left side.

Tap for more steps...

Step 4.2.1

Cancel the common factor of $2$ .

Tap for more steps...

Step 4.2.1.1

Cancel the common factor.

$\frac{2 a}{2} = \frac{4}{2}$

Step 4.2.1.2

Divide $a$ by $1$ .

$a = \frac{4}{2}$

Step 4.3

Simplify the right side.

Tap for more steps...

Step 4.3.1

Divide $4$ by $2$ .

$a = 2$

Step 5

Exclude the solutions that do not make $\frac{1}{a + 2} + \frac{1}{a - 2} = \frac{4}{a^{2} - 4}$ true.

$No solution$