Question

if x-2y=11and xy=8find x3-8y3​

Answer 1

x-2y=11

cubing both sides,

x³-8y³-3.x.2y(x-2y)=1331

or, x³-8y³-6.8.11=1331 [∵, xy=8 and x-2y=11]

or, x³-8y³=1331+528

or, x³-8y³=1859