# What is the standard form of  y= (x - 40) (x + 4) ?

Jan 3, 2016

$y = {x}^{2} - 36 x - 160$

#### Explanation:

If you like, you can use FOIL to help multiply this out:

$y = \left(x - 40\right) \left(x + 4\right)$

$= \stackrel{\text{First" overbrace(x*x) + stackrel "Outside" overbrace(x*4) + stackrel "Inside" overbrace(-40*x) + stackrel "Last}}{\overbrace{- 40 \cdot 4}}$

$= {x}^{2} + 4 x - 40 x - 160$

$= {x}^{2} - 36 x - 160$