If $x^2+x+1=0 $, then find the value of $(x^3+1/x^3)^3$? 
If $x^2+x+1=0 $, then find the value of $(x^3+1/x^3)^3$

This thing doesn't make sense how should I use first identity to find the second one.

$x^2+x+1=0 \to x+1/x=-1 \to (x+1/x)^3 = -1\to x^3 + 3(x+1/x) + 1/x^3 = -1\to x^3+1/x^3 = 2 \to (x^3+1/x^3)^3 = 2^3 = 8$
