5x^4+x^2-18=0

Solution for 5x^4+x^2-18=0 equation:

Simplifying
5x4 + x2 + -18 = 0

Reorder the terms:
-18 + x2 + 5x4 = 0

Solving
-18 + x2 + 5x4 = 0

Solving for variable 'x'.

Factor a trinomial.
(-2 + -1x2)(9 + -5x2) = 0

Subproblem 1
Set the factor '(-2 + -1x2)' equal to zero and attempt to solve:

Simplifying
-2 + -1x2 = 0

Solving
-2 + -1x2 = 0

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

Add '2' to each side of the equation.
-2 + 2 + -1x2 = 0 + 2

Combine like terms: -2 + 2 = 0
0 + -1x2 = 0 + 2
-1x2 = 0 + 2

Combine like terms: 0 + 2 = 2
-1x2 = 2

Divide each side by '-1'.
x2 = -2

Simplifying
x2 = -2

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 '(9 + -5x2)' equal to zero and attempt to solve:

Simplifying
9 + -5x2 = 0

Solving
9 + -5x2 = 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 + -5x2 = 0 + -9

Combine like terms: 9 + -9 = 0
0 + -5x2 = 0 + -9
-5x2 = 0 + -9

Combine like terms: 0 + -9 = -9
-5x2 = -9

Divide each side by '-5'.
x2 = 1.8

Simplifying
x2 = 1.8

Take the square root of each side:
x = {-1.341640787, 1.341640787}
Solution
x = {-1.341640787, 1.341640787}