81b^2-5=-1

Solution for 81b^2-5=-1 equation:

Simplifying
81b2 + -5 = -1

Reorder the terms:
-5 + 81b2 = -1

Solving
-5 + 81b2 = -1

Solving for variable 'b'.

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

Add '5' to each side of the equation.
-5 + 5 + 81b2 = -1 + 5

Combine like terms: -5 + 5 = 0
0 + 81b2 = -1 + 5
81b2 = -1 + 5

Combine like terms: -1 + 5 = 4
81b2 = 4

Divide each side by '81'.
b2 = 0.04938271605

Simplifying
b2 = 0.04938271605

Take the square root of each side:
b = {-0.222222222, 0.222222222}