-12=x^2-21

Solution for -12=x^2-21 equation:

Simplifying
-12 = x2 + -21

Reorder the terms:
-12 = -21 + x2

Solving
-12 = -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.
-12 + -1x2 = -21 + x2 + -1x2

Combine like terms: x2 + -1x2 = 0
-12 + -1x2 = -21 + 0
-12 + -1x2 = -21

Add '12' to each side of the equation.
-12 + 12 + -1x2 = -21 + 12

Combine like terms: -12 + 12 = 0
0 + -1x2 = -21 + 12
-1x2 = -21 + 12

Combine like terms: -21 + 12 = -9
-1x2 = -9

Divide each side by '-1'.
x2 = 9

Simplifying
x2 = 9

Take the square root of each side:
x = {-3, 3}