Question

What is the factorization of the expression below?

4x2 - 81

Answer 1

using the difference of squares:
(a2−b2)=(a+b)(a−b)

Think of
4x2=2x×2x
and
81=9×9

If 4x^2=a^2 and 81=b^2, you get
a=2x and b=9
So, factored would be (2x+9)(2x-9)

Answer 2

Hope this helps ;P