x^4=11x^2-18

Solution for x^4=11x^2-18 equation:

Simplifying
x4 = 11x2 + -18

Reorder the terms:
x4 = -18 + 11x2

Solving
x4 = -18 + 11x2

Solving for variable 'x'.

Reorder the terms:
18 + -11x2 + x4 = -18 + 11x2 + 18 + -11x2

Reorder the terms:
18 + -11x2 + x4 = -18 + 18 + 11x2 + -11x2

Combine like terms: -18 + 18 = 0
18 + -11x2 + x4 = 0 + 11x2 + -11x2
18 + -11x2 + x4 = 11x2 + -11x2

Combine like terms: 11x2 + -11x2 = 0
18 + -11x2 + x4 = 0

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

Factor a difference between two squares.
(2 + -1x2)((3 + x)(3 + -1x)) = 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

Take the square root of each side:
x = {-1.414213562, 1.414213562}
Subproblem 2
Set the factor '(3 + x)' equal to zero and attempt to solve:

Simplifying
3 + x = 0

Solving
3 + x = 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 + x = 0 + -3

Combine like terms: 3 + -3 = 0
0 + x = 0 + -3
x = 0 + -3

Combine like terms: 0 + -3 = -3
x = -3

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

Simplifying
3 + -1x = 0

Solving
3 + -1x = 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 + -1x = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -1x = 0 + -3
-1x = 0 + -3

Combine like terms: 0 + -3 = -3
-1x = -3

Divide each side by '-1'.
x = 3

Simplifying
x = 3
Solution
x = {-1.414213562, 1.414213562, -3, 3}