81r^2-1=

Solution for 81r^2-1= equation:

Simplifying
81r2 + -1 = 0

Reorder the terms:
-1 + 81r2 = 0

Solving
-1 + 81r2 = 0

Solving for variable 'r'.

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

Add '1' to each side of the equation.
-1 + 1 + 81r2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + 81r2 = 0 + 1
81r2 = 0 + 1

Combine like terms: 0 + 1 = 1
81r2 = 1

Divide each side by '81'.
r2 = 0.01234567901

Simplifying
r2 = 0.01234567901

Take the square root of each side:
r = {-0.111111111, 0.111111111}