Question 139544
{{{t^4-6t^2-4=0}}}


Let {{{x=t^2}}}, then substitute into {{{t^4-6t^2-4=0}}} giving {{{x^2-6x-4=0}}}


Solve the quadratic in x by either completing the square or using the quadradic formula (this one doesn't factor neatly).  You will find two roots in x.


Set each of these roots equal to {{{t^2}}} and then solve each equation for t, remembering to consider the positive and negative root in each case.


You will end up with 4 roots, which was expected because you started with a quartic (4th degree) equation.