.81-p^2=0

Solution for .81-p^2=0 equation:

Simplifying
0.81 + -1p2 = 0

Solving
0.81 + -1p2 = 0

Solving for variable 'p'.

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

Add '-0.81' to each side of the equation.
0.81 + -0.81 + -1p2 = 0 + -0.81

Combine like terms: 0.81 + -0.81 = 0.00
0.00 + -1p2 = 0 + -0.81
-1p2 = 0 + -0.81

Combine like terms: 0 + -0.81 = -0.81
-1p2 = -0.81

Divide each side by '-1'.
p2 = 0.81

Simplifying
p2 = 0.81

Take the square root of each side:
p = {-0.9, 0.9}