Simplify (x^2-36)/(x^2+12x+36)

$\frac{x^{2} - 36}{x^{2} + 12 x + 36}$

Step 1

Simplify the numerator.

Rewrite $36$ as $6^{2}$ .

$\frac{x^{2} - 6^{2}}{x^{2} + 12 x + 36}$

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 $b = 6$ .

$\frac{(x + 6) (x - 6)}{x^{2} + 12 x + 36}$

Step 2

Factor using the perfect square rule.

Rewrite $36$ as $6^{2}$ .

$\frac{(x + 6) (x - 6)}{x^{2} + 12 x + 6^{2}}$

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

$12 x = 2 \cdot x \cdot 6$

Rewrite the polynomial.

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

Factor using the perfect square trinomial rule $a^{2} + 2 a b + b^{2} = {(a + b)}^{2}$ , where $a = x$ and $b = 6$ .

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

Step 3

Cancel the common factors.

Factor $x + 6$ out of ${(x + 6)}^{2}$ .

$\frac{(x + 6) (x - 6)}{(x + 6) (x + 6)}$

Cancel the common factor.

$\frac{(x + 6) (x - 6)}{(x + 6) (x + 6)}$

Rewrite the expression.

$\frac{x - 6}{x + 6}$