0=r^2-129.6

Solution for 0=r^2-129.6 equation:

Simplifying
0 = r2 + -129.6

Reorder the terms:
0 = -129.6 + r2

Solving
0 = -129.6 + r2

Solving for variable 'r'.

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

Add '-1r2' to each side of the equation.
0 + -1r2 = -129.6 + r2 + -1r2
Remove the zero:
-1r2 = -129.6 + r2 + -1r2

Combine like terms: r2 + -1r2 = 0
-1r2 = -129.6 + 0
-1r2 = -129.6

Divide each side by '-1'.
r2 = 129.6

Simplifying
r2 = 129.6

Take the square root of each side:
r = {-11.384199577, 11.384199577}