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

Answer:

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")#