$$x+\frac{1}{x}-1=0; x^{81}+x^{-87}+x^{168}=?$$
$x=\frac{-\sqrt{3}i+1}{2}\approx 0.5-0.866025404i\text{, }y=-1$
$x=\frac{1+\sqrt{3}i}{2}\approx 0.5+0.866025404i\text{, }y=-1$
