b) x^2 + 8xy + 16y^2 – 4z^2.
b) x2 + 8xy + 16y2 – 4z2.
b) x2 + 8xy + 16y2 – 4z2
= (x2 + 8xy + 16y2) – 4z2
= (x + 4y)2 – (2z)2
= (x + 4y – 2z)(x + 4y + 2z).