Question 551480
{{{x^4-6x^2-27=0}}}
Factoring
{{{(x^2-9)(x^2+3)=0}}}
Two of 4 solutions come from
{{{x^2-9=0}}} --> {{{x=3}}} and {{{x=-3}}}
The other two solutions come from
{{{x^2+3=0}}} --> {{{x=i*sqrt(3)}}} and {{{x=-i*sqrt(3)}}}