7x^4-21x^2=

Solution for 7x^4-21x^2= equation:

Simplifying
7x4 + -21x2 = 0

Reorder the terms:
-21x2 + 7x4 = 0

Solving
-21x2 + 7x4 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '7x2'.
7x2(-3 + x2) = 0

Ignore the factor 7.
Subproblem 1
Set the factor 'x2' equal to zero and attempt to solve:

Simplifying
x2 = 0

Solving
x2 = 0

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

Simplifying
x2 = 0

Take the square root of each side:
x = {0}
Subproblem 2
Set the factor '(-3 + x2)' equal to zero and attempt to solve:

Simplifying
-3 + x2 = 0

Solving
-3 + x2 = 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 + x2 = 0 + 3

Combine like terms: -3 + 3 = 0
0 + x2 = 0 + 3
x2 = 0 + 3

Combine like terms: 0 + 3 = 3
x2 = 3

Simplifying
x2 = 3

Take the square root of each side:
x = {-1.732050808, 1.732050808}
Solution
x = {0, -1.732050808, 1.732050808}