Question 461158
The factorization of {{{27x^4-3x^2-4}}} is {{{(9x^2 - 4)(3x^2 + 1)}}}.  Hence the equation becomes {{{(9x^2 - 4)(3x^2 + 1) = 0}}}, or {{{(3x - 2)(3x + 2)(3x^2 + 1) = 0}}}.  You should know what to do next...