x*x-39=42

Solution for x*x-39=42 equation:

Simplifying
x * x + -39 = 42

Multiply x * x
x2 + -39 = 42

Reorder the terms:
-39 + x2 = 42

Solving
-39 + x2 = 42

Solving for variable 'x'.

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

Add '39' to each side of the equation.
-39 + 39 + x2 = 42 + 39

Combine like terms: -39 + 39 = 0
0 + x2 = 42 + 39
x2 = 42 + 39

Combine like terms: 42 + 39 = 81
x2 = 81

Simplifying
x2 = 81

Take the square root of each side:
x = {-9, 9}