25x^4-81=0

Solution for 25x^4-81=0 equation:

Simplifying
25x4 + -81 = 0

Reorder the terms:
-81 + 25x4 = 0

Solving
-81 + 25x4 = 0

Solving for variable 'x'.

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

Add '81' to each side of the equation.
-81 + 81 + 25x4 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 25x4 = 0 + 81
25x4 = 0 + 81

Combine like terms: 0 + 81 = 81
25x4 = 81

Divide each side by '25'.
x4 = 3.24

Simplifying
x4 = 3.24

Reorder the terms:
-3.24 + x4 = 3.24 + -3.24

Combine like terms: 3.24 + -3.24 = 0.00
-3.24 + x4 = 0.00

Factor a difference between two squares.
(1.8 + x2)(-1.8 + x2) = 0.00

Subproblem 1
Set the factor '(1.8 + x2)' equal to zero and attempt to solve:

Simplifying
1.8 + x2 = 0

Solving
1.8 + x2 = 0

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

Add '-1.8' to each side of the equation.
1.8 + -1.8 + x2 = 0 + -1.8

Combine like terms: 1.8 + -1.8 = 0.0
0.0 + x2 = 0 + -1.8
x2 = 0 + -1.8

Combine like terms: 0 + -1.8 = -1.8
x2 = -1.8

Simplifying
x2 = -1.8

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 '(-1.8 + x2)' equal to zero and attempt to solve:

Simplifying
-1.8 + x2 = 0

Solving
-1.8 + x2 = 0

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

Add '1.8' to each side of the equation.
-1.8 + 1.8 + x2 = 0 + 1.8

Combine like terms: -1.8 + 1.8 = 0.0
0.0 + x2 = 0 + 1.8
x2 = 0 + 1.8

Combine like terms: 0 + 1.8 = 1.8
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}