<s>[INST] 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.
 [/INST] HINT:  Use $a^3+b^3=(a+b)(a^2+b^2-ab)$ and also the fact that if $x^2+x+1=0$, then $x+\frac1x$=$-1$.
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