# What is the standard form of  y= (x + 2)(x – 2) ?

Sep 19, 2016

$y = {x}^{2} - 4$

#### Explanation:

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

Distribute (FOIL)
$y = {x}^{2} - 2 x + 2 x - 4$

Combine like terms
$y = {x}^{2} - 4$

This is typically what's called standard form.

It is also can be written as
$y = {\left(x - 0\right)}^{2} - 4$.
This is usually called "vertex form" with the vertex at $\left(0 , - 4\right)$ but some textbooks refer to it as "standard form".