21=x^2

Solution for 21=x^2 equation:

Simplifying
21 = x2

Solving
21 = x2

Solving for variable 'x'.

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

Add '-1x2' to each side of the equation.
21 + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
21 + -1x2 = 0

Add '-21' to each side of the equation.
21 + -21 + -1x2 = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -1x2 = 0 + -21
-1x2 = 0 + -21

Combine like terms: 0 + -21 = -21
-1x2 = -21

Divide each side by '-1'.
x2 = 21

Simplifying
x2 = 21

Take the square root of each side:
x = {-4.582575695, 4.582575695}