Question

How do you factor: #y= x^2-4 #?

Answer 1

`(x+2)(x-2)`

Explanation:

Notice we can write:

`x^2-4\ \ \ \` as `\ \ \ \ x^2-2^2`

This is the difference of two squares:

`a^2-b^2=(a+b)(a-b)`

`:.`

`x^2-2^2=(x+2)(x-2)`