Question

Evaluate x³ + y³ + z³ −3xyz when x = −2, y = −1 and z = 3.

Answer 1

$\begin{array}{l}\text{We have:}\\ x^3+y^3+z^3-3xyz\\ =(-2{)}^3+(-1{)}^3+(3{)}^3-3\times (-2)\times (-1)\times 3\\ =-8-1+27-18\\ =-27+27\\ =0\end{array}$