Question 397083
{{{4x^4-16x^2+15 = (2x^2 - 5  )( 2x^2 - 3) =0}}}
==> {{{2x^2 - 5  = 0}}} or {{{2x^2 - 3 = 0}}}
==> {{{x^2 = 5/2}}} or {{{x^2  = 3/2}}}
==> {{{x = sqrt(5)/2}}}, {{{-sqrt(5)/2}}}, {{{sqrt(3)/2}}}, and {{{-sqrt(3)/2}}}.