Question

If x-2y=11 and xy=8 then find x^3-8y^3

Answer 1

Given
x - 2y = 11 and xy = 8

x - 2y = 11
Cubing on both sides
(x - 2y)³ = (11)³
x³ - 8y³ - 3*x*8y (x - 2y) = 1221
x³ - 8y³ - 24xy (11) = 1221
x³ - 8y³ - 24(8) (11) = 1221
x³ - 8y³ - 2112 = 1221
x³ - 8y³ = 1221+2112
x³ - 8y³ = 3333

Hope this helps you.