Question 310460
Let {{{u=x^2}}}, then {{{u^2=x^4}}}
{{{ x^4+6x^2-27=0}}}
{{{ u^2+6u-27=0}}}
Factor.
{{{(u+9)(u-3)}}}
Two solutions:
{{{u+9=0}}}
{{{u=-9}}}
{{{x^2=-9}}}
{{{x=0 +- 3i}}}
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{{{u-3=0}}}
{{{u=3}}}
{{{x^2=3}}}
{{{x=0 +- sqrt(3)}}}
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({{{-sqrt(3)}}},{{{sqrt(3)}}},{{{-3i}}}, {{{3i}}})