Question

How do you factor completely `4x² - 36`?

Answer 1

`4x^2-36=4(x-3)(x+3)`

Explanation:

The difference of squares identity can be written:

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

So we find:

`4x^2-36`

`=4(x^2-9)`

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

`=4(x-3)(x+3)`