FOIL stands for:

First

Outside

Inside

Last

referring to the order in which you multiply the terms using the distributive law.

**Example:** Expand
(2x-1)(1x+5) a.k.a.
(2x-1)(x+5)

First term: (2x)(1x) = 2x^{2}

Outside term: (2x)(5) = 10x

Inside term: (-1)(1x) = -1x

Last term: (-1)(5) = -5

Adding everything together we get:

2x^{2} + 10x - 1x - 5

= 2x^{2} + 9x - 5

**Difference of squares**

If you have something like (x+5)(x-5) you
will notice that it expands to
x^{2}+0x-25.
But, since the coefficient in front
of the x is 0, we write it as
x^{2}-25.

Copyright © 2011 - Mathwizz.com all rights reserved