4x^4+5x^2-9=0

Solution for 4x^4+5x^2-9=0 equation:

Simplifying
4x4 + 5x2 + -9 = 0

Reorder the terms:
-9 + 5x2 + 4x4 = 0

Solving
-9 + 5x2 + 4x4 = 0

Solving for variable 'x'.

Factor a trinomial.
(-9 + -4x2)(1 + -1x2) = 0

Factor a difference between two squares.
(-9 + -4x2)((1 + x)(1 + -1x)) = 0

Subproblem 1
Set the factor '(-9 + -4x2)' equal to zero and attempt to solve:

Simplifying
-9 + -4x2 = 0

Solving
-9 + -4x2 = 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 + -4x2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -4x2 = 0 + 9
-4x2 = 0 + 9

Combine like terms: 0 + 9 = 9
-4x2 = 9

Divide each side by '-4'.
x2 = -2.25

Simplifying
x2 = -2.25

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 + x)' equal to zero and attempt to solve:

Simplifying
1 + x = 0

Solving
1 + x = 0

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

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

Combine like terms: 1 + -1 = 0
0 + x = 0 + -1
x = 0 + -1

Combine like terms: 0 + -1 = -1
x = -1

Simplifying
x = -1
Subproblem 3
Set the factor '(1 + -1x)' equal to zero and attempt to solve:

Simplifying
1 + -1x = 0

Solving
1 + -1x = 0

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

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

Combine like terms: 1 + -1 = 0
0 + -1x = 0 + -1
-1x = 0 + -1

Combine like terms: 0 + -1 = -1
-1x = -1

Divide each side by '-1'.
x = 1

Simplifying
x = 1
Solution
x = {-1, 1}