How do you factor (a+b)2^-4b2^?

Question

my original question with is (a+b)-4b2^ is actually wrong. This is the right question so how do you do it?

Answer 1

Let (a + b) = c
c² - (2b)²
(c - 2b) (c + 2b)
(a + b - 2b)(a + b + 2b)
(a - b)(a + 3b)

Answer 2

This is the difference of two squares:
(A^2 - B^2) = (A + B) (A - B)

(a+b)2^-4b2^ = (a + b + 2b) (a + b - 2b)
= (a+3b)(a - b)

Answer 3

(a+b)^2-4b^2

a^2+2ab+b^2-4b^2

a^2+2ab-3b^2

(a+3b)(a-b)