(ab+9)(ab-9)=

Solution for (ab+9)(ab-9)= equation:

Simplifying
(ab + 9)(ab + -9) = 0

Reorder the terms:
(9 + ab)(ab + -9) = 0

Reorder the terms:
(9 + ab)(-9 + ab) = 0

Multiply (9 + ab) * (-9 + ab)
(9(-9 + ab) + ab(-9 + ab)) = 0
((-9 * 9 + ab * 9) + ab(-9 + ab)) = 0
((-81 + 9ab) + ab(-9 + ab)) = 0
(-81 + 9ab + (-9 * ab + ab * ab)) = 0
(-81 + 9ab + (-9ab + a2b2)) = 0

Combine like terms: 9ab + -9ab = 0
(-81 + 0 + a2b2) = 0
(-81 + a2b2) = 0

Solving
-81 + a2b2 = 0

Solving for variable 'a'.

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

Add '81' to each side of the equation.
-81 + 81 + a2b2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + a2b2 = 0 + 81
a2b2 = 0 + 81

Combine like terms: 0 + 81 = 81
a2b2 = 81

Divide each side by 'b2'.
a2 = 81b-2

Simplifying
a2 = 81b-2

Take the square root of each side:
a = {-9b-1, 9b-1}