90+90+99+x*x=360

Solution for 90+90+99+x*x=360 equation:

Simplifying
90 + 90 + 99 + x * x = 360

Multiply x * x
90 + 90 + 99 + x2 = 360

Combine like terms: 90 + 90 = 180
180 + 99 + x2 = 360

Combine like terms: 180 + 99 = 279
279 + x2 = 360

Solving
279 + x2 = 360

Solving for variable 'x'.

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

Add '-279' to each side of the equation.
279 + -279 + x2 = 360 + -279

Combine like terms: 279 + -279 = 0
0 + x2 = 360 + -279
x2 = 360 + -279

Combine like terms: 360 + -279 = 81
x2 = 81

Simplifying
x2 = 81

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