# How do you solve x^3-81x=0 ?

It is ${x}^{3} - 81 x = 0 \implies x \left({x}^{2} - {9}^{2}\right) = 0 \implies x \cdot \left(x - 9\right) \left(x + 9\right) = 0 \implies x = 0 \mathmr{and} x = 9 \mathmr{and} x = - 9$