81r^2-49=

Solution for 81r^2-49= equation:

Simplifying
81r2 + -49 = 0

Reorder the terms:
-49 + 81r2 = 0

Solving
-49 + 81r2 = 0

Solving for variable 'r'.

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

Add '49' to each side of the equation.
-49 + 49 + 81r2 = 0 + 49

Combine like terms: -49 + 49 = 0
0 + 81r2 = 0 + 49
81r2 = 0 + 49

Combine like terms: 0 + 49 = 49
81r2 = 49

Divide each side by '81'.
r2 = 0.6049382716

Simplifying
r2 = 0.6049382716

Take the square root of each side:
r = {-0.777777778, 0.777777778}