Question

How do you factor `4x^2 -9`?

Answer 1

This is a difference of squares:

`4x^2-9 = (2x)^2 - 3^2`

So you can use the difference of squares identity

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

to find...

`(2x)^2 - 3^2 = (2x-3)(2x+3)`