Question

How do you find the value of `x^3+y^3-12xy+64` when `x+y=-4`?

Answer 1

`0`

Explanation:

We know that

`(x^3 + y^3)/(x+y)= x^2 - x y + y^2` then

`x^3+y^3 = -4(x^2 - x y + y^2)` then

`x^3+y^3-12xy+64 = -4(x^2 - x y + y^2) -12xy+64 =`
`-4 (x + y-4) (4 + x + y) = 0`