Question

x-y =2 ,xy =15 then x^3-y^3?

Answer 1

given,
x-y = 2
cubing both sides
(x-y)³ = 2³
=> x³- y³ -3xy ( x-y) = 8
=> x³ - y³ - 3×15×2= 8.
=> x³ - y³ - 90 = 8
=>x³ - y³ = 8+90
=> x³ - y³ = 98