Question

How would you factor a quadratic expression like 9x^2-4

Answer 1

Hello, we need to see it as a difference of two squares as we know that for all a and b real numbers

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

So, here

$9x^2-4=(3x)^2-2^2=(3x-2)(3x+2)$

Voila !

Thank you