Question 180459
Use a subsitution to transform this equation to a quadratic equation.
Let {{{z=x^3}}}, then
{{{x^6-3x^3-18=z^2-3z-18=0}}}
{{{(z-6)(z+3)=0}}}
First solution:
{{{z-6=0}}}
{{{z=6}}}
{{{x^3=6}}}
{{{x=6^(1/3)}}}
Second solution:
{{{z+3=0}}}
{{{z=-3}}}
{{{x^3=-3}}}
{{{x=-3^(1/3)}}}