Question

when factored completely, what are the factors of 4x^2-16 ?

Answer 1

$4x^2-16=\\ 4(x^2-4)=\\ 4(x-2)(x+2)$

Answer 2

$Use:a^2-b^2=(a-b)(a+b)\\\\4x^2-16=4(x^2-4)=4(x^2-2^2)=\boxed{4(x-2)(x+2)}$