x*x-12=78

Solution for x*x-12=78 equation:

Simplifying
x * x + -12 = 78

Multiply x * x
x2 + -12 = 78

Reorder the terms:
-12 + x2 = 78

Solving
-12 + x2 = 78

Solving for variable 'x'.

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

Add '12' to each side of the equation.
-12 + 12 + x2 = 78 + 12

Combine like terms: -12 + 12 = 0
0 + x2 = 78 + 12
x2 = 78 + 12

Combine like terms: 78 + 12 = 90
x2 = 90

Simplifying
x2 = 90

Take the square root of each side:
x = {-9.486832981, 9.486832981}