Question

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

Answer 1

(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`

Answer 2

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")`