# How do you factor 144-x^2?

Jun 10, 2015

$\left(12 + x\right) \left(12 - x\right)$

#### Explanation:

I can "see" in this expression this general one:
$\left(a + b\right) \left(a - b\right) = {a}^{2} - {b}^{2}$
where:
${a}^{2} = 144$ so that $a = 12$
${b}^{2} = {x}^{2}$ so that $b = x$
Using these options I get:
$\left(12 + x\right) \left(12 - x\right) = \left(12 \cdot 12\right) \cancel{- \left(12 \cdot x\right)} \cancel{+ \left(12 \cdot x\right)} - \left(x \cdot x\right) =$
$= 144 - {x}^{2}$