x^2+y^2+(x^2-y^2)=13+7

Solution for x^2+y^2+(x^2-y^2)=13+7 equation:

Simplifying
x2 + y2 + (x2 + -1y2) = 13 + 7

Remove parenthesis around (x2 + -1y2)
x2 + y2 + x2 + -1y2 = 13 + 7

Reorder the terms:
x2 + x2 + y2 + -1y2 = 13 + 7

Combine like terms: x2 + x2 = 2x2
2x2 + y2 + -1y2 = 13 + 7

Combine like terms: y2 + -1y2 = 0
2x2 + 0 = 13 + 7
2x2 = 13 + 7

Combine like terms: 13 + 7 = 20
2x2 = 20

Solving
2x2 = 20

Solving for variable 'x'.

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

Divide each side by '2'.
x2 = 10

Simplifying
x2 = 10

Take the square root of each side:
x = {-3.16227766, 3.16227766}