Question 1091093
Let y = x^4


f(x) = 25y^2 - 234y + 81
= (25y - 9)(y - 9)


x^4 = 9 ---> x = sqrt(3), -sqrt(3), {{{i * sqrt(3)}}}, {{{-i * sqrt(3)}}}

x^4 = 9/25 ---> x = 3sqrt(5)/5, -3sqrt(5)/5, {{{3i * sqrt(5)/5}}}, {{{-3i * sqrt(5)/5}}}