Use FOIL to solve the problem (x-2)(x+2) last ?

2 Answers
Feb 9, 2018

(x-2)(x+2)

1) Do x times x = x^2
2) Do x times 2 = 2x
3) Do -2 times x = -2x
4) Do -2 times 2 = -4

5) Put all of those terms in order
x^2+2x-2x-4

6) Add or subtract like terms
x^2-4

Feb 9, 2018

This is a different format but is still foil

x^2-2^2

Explanation:

color(purple)("Answering the question")

color(blue)((x-2))color(green)( (x+2) )

Multiply everything inside the right brackets by everything in the left.

color(green)(color(blue)(x ) (x+2) color(white)("ddd")color(blue)( -2) (x+2) )

color(green)(x^2+2xcolor(white)("d")color(white)("ddd")-2x-4

color(white)("dddddd")color(green)(x^2-4)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
color(purple)("Foot note")

What follows is really worth committing to memory. It shows up a lot!

color(red)("The above of "x^2-4" is the same as "x^2-2^2)

Compare this

color(red)(x^2-2^2)
color(purple)(a^2-b^2=(a-b)(a+b) larr" Commit to memory")