r^2+8-90=5

Solution for r^2+8-90=5 equation:

Simplifying
r2 + 8 + -90 = 5

Reorder the terms:
8 + -90 + r2 = 5

Combine like terms: 8 + -90 = -82
-82 + r2 = 5

Solving
-82 + r2 = 5

Solving for variable 'r'.

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

Add '82' to each side of the equation.
-82 + 82 + r2 = 5 + 82

Combine like terms: -82 + 82 = 0
0 + r2 = 5 + 82
r2 = 5 + 82

Combine like terms: 5 + 82 = 87
r2 = 87

Simplifying
r2 = 87

Take the square root of each side:
r = {-9.327379053, 9.327379053}