5x^4+42x^2-27=0

Solution for 5x^4+42x^2-27=0 equation:

Simplifying
5x4 + 42x2 + -27 = 0

Reorder the terms:
-27 + 42x2 + 5x4 = 0

Solving
-27 + 42x2 + 5x4 = 0

Solving for variable 'x'.

Factor a trinomial.
(-9 + -1x2)(3 + -5x2) = 0

Subproblem 1
Set the factor '(-9 + -1x2)' equal to zero and attempt to solve:

Simplifying
-9 + -1x2 = 0

Solving
-9 + -1x2 = 0

Move all terms containing x to the left, all other terms to the right.

Add '9' to each side of the equation.
-9 + 9 + -1x2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -1x2 = 0 + 9
-1x2 = 0 + 9

Combine like terms: 0 + 9 = 9
-1x2 = 9

Divide each side by '-1'.
x2 = -9

Simplifying
x2 = -9

The solution to this equation could not be determined.

This subproblem is being ignored because a solution could not be determined.
Subproblem 2
Set the factor '(3 + -5x2)' equal to zero and attempt to solve:

Simplifying
3 + -5x2 = 0

Solving
3 + -5x2 = 0

Move all terms containing x to the left, all other terms to the right.

Add '-3' to each side of the equation.
3 + -3 + -5x2 = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -5x2 = 0 + -3
-5x2 = 0 + -3

Combine like terms: 0 + -3 = -3
-5x2 = -3

Divide each side by '-5'.
x2 = 0.6

Simplifying
x2 = 0.6

Take the square root of each side:
x = {-0.774596669, 0.774596669}
Solution
x = {-0.774596669, 0.774596669}