Question

find the value of x^3+y^3-12xy+64 when x+y= -4

Answer 1

x+y = -4
Cubing on both sides
(x+y)³ = (-4)³
x³+y³+3xy(x+y) = -64
x³+y³+3xy(-4) = -64
x³+y³-12xy = -64
x³+y³-12xy + 64 = 0