2x^2-81=x^2

Solution for 2x^2-81=x^2 equation:

Simplifying
2x2 + -81 = x2

Reorder the terms:
-81 + 2x2 = x2

Solving
-81 + 2x2 = 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.
-81 + 2x2 + -1x2 = x2 + -1x2

Combine like terms: 2x2 + -1x2 = 1x2
-81 + 1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
-81 + 1x2 = 0

Add '81' to each side of the equation.
-81 + 81 + 1x2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 1x2 = 0 + 81
1x2 = 0 + 81

Combine like terms: 0 + 81 = 81
1x2 = 81

Divide each side by '1'.
x2 = 81

Simplifying
x2 = 81

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