c) 4x^3 – y^3 + 4x^2y – xy^2
c) 4x3 – y3 + 4x2y – xy2
c) 4x3 – y3 + 4x2y – xy2
= (4x3 + 4x2y) – (y3 + xy2)
= 4x2(x + y) ‒ y2(y + x)
= (x + y)(4x2 ‒ y2)
= (x + y)[(2x)2 ‒ y2]
= (x + y)(2x + y)(2x ‒ y).