Solve this cubic equation...

To be precise, its a 6 degree equation albeit an easy one.

put x²+x-2 = a
and 2x²-x-1 = b
then 3x²-3 =(a+b)
or 3(x²-1) = (a+b)
now the expression become a³+b³ = (a+b)³
now solve this expression.
3ab(a+b) = 0
means
a = 0
b = 0
and (a+b) = 0
actually this solution was given by hsbhatt sir in another forum.

that was the way I thought about the problem..