# How do you factor: y= x^2-4 ?

Mar 22, 2018

$\left(x + 2\right) \left(x - 2\right)$

#### Explanation:

Notice we can write:

${x}^{2} - 4 \setminus \setminus \setminus \setminus$ as $\setminus \setminus \setminus \setminus {x}^{2} - {2}^{2}$

This is the difference of two squares:

${a}^{2} - {b}^{2} = \left(a + b\right) \left(a - b\right)$

$\therefore$

${x}^{2} - {2}^{2} = \left(x + 2\right) \left(x - 2\right)$