Question 59030
{{{x^4-8x^2+7=0}}}  Factor, (there are other methods.)
{{{x^4-x^2-7x^2+7=0}}}
{{{(x^4-x^2)+(-7x^2+7)=0}}}
{{{x^2(x^2-1)-7(x^2-1)=0}}}
{{{(x^2-1)(x^2-7)=0}}}  Set each parenthesese equal to 0 and solve for x.
{{{x^2-1=0}}} and {{{x^2-7=0}}}
{{{x^2=1}}} and {{{x^2=7}}}
{{{sqrt(x^2)=+-sqrt(1)}}} and {{{sqrt(x^2)=+-sqrt(7)}}}
{{{x=-1}}} and {{{x=1}}}  and  {{{x=-sqrt(7)}}} and {{{x=sqrt(7)}}}
Happy Calculating!!!