20.25=r^2

Solution for 20.25=r^2 equation:

Simplifying
20.25 = r2

Solving
20.25 = 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.
20.25 + -1r2 = r2 + -1r2

Combine like terms: r2 + -1r2 = 0
20.25 + -1r2 = 0

Add '-20.25' to each side of the equation.
20.25 + -20.25 + -1r2 = 0 + -20.25

Combine like terms: 20.25 + -20.25 = 0.00
0.00 + -1r2 = 0 + -20.25
-1r2 = 0 + -20.25

Combine like terms: 0 + -20.25 = -20.25
-1r2 = -20.25

Divide each side by '-1'.
r2 = 20.25

Simplifying
r2 = 20.25

Take the square root of each side:
r = {-4.5, 4.5}