Answer:
( 9w - 2z)^2
Step-by-step explanation:
81w^2 - 36wz + 4z^2
Rewriting as
(9w)^2 - 2 * 9 w 2z + (2z)^2
We recognize that this is a perfect square binomial
a^2 -2ab + b^2 is a perfect square binomial because it factors to (a - b)^2
let a = 9w b = 2z
81w^2 - 36wz + 4z^2 = ( 9w - 2z)^2
