x^4+x^2=72

Solution for x^4+x^2=72 equation:

Simplifying
x4 + x2 = 72

Reorder the terms:
x2 + x4 = 72

Solving
x2 + x4 = 72

Solving for variable 'x'.

Reorder the terms:
-72 + x2 + x4 = 72 + -72

Combine like terms: 72 + -72 = 0
-72 + x2 + x4 = 0

Factor a trinomial.
(-9 + -1x2)(8 + -1x2) = 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 '(8 + -1x2)' equal to zero and attempt to solve:

Simplifying
8 + -1x2 = 0

Solving
8 + -1x2 = 0

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

Add '-8' to each side of the equation.
8 + -8 + -1x2 = 0 + -8

Combine like terms: 8 + -8 = 0
0 + -1x2 = 0 + -8
-1x2 = 0 + -8

Combine like terms: 0 + -8 = -8
-1x2 = -8

Divide each side by '-1'.
x2 = 8

Simplifying
x2 = 8

Take the square root of each side:
x = {-2.828427125, 2.828427125}
Solution
x = {-2.828427125, 2.828427125}