$x+y+z=2$ and $x y+y z+z x=-11$, then the value of $x^3+y^3+z^3-3 x y z$ is :

74

$x+y+z=2$ and $x y+y z+z x=-11$

The value of $x^3+y^3+z^3-3 x y z$ is = ?

If the number of equations are less than the number of variables then we can put the extra variables according to our choice = 

So here two equations given and three variables are present so put z = 0

$x+y=2$ and $x y=-11$

The value of $x^3+y^3$ is = 2³ - (3 × -11 × 2) =  74