(3b-9)(3b+9)=

Solution for (3b-9)(3b+9)= equation:

Simplifying
(3b + -9)(3b + 9) = 0

Reorder the terms:
(-9 + 3b)(3b + 9) = 0

Reorder the terms:
(-9 + 3b)(9 + 3b) = 0

Multiply (-9 + 3b) * (9 + 3b)
(-9(9 + 3b) + 3b * (9 + 3b)) = 0
((9 * -9 + 3b * -9) + 3b * (9 + 3b)) = 0
((-81 + -27b) + 3b * (9 + 3b)) = 0
(-81 + -27b + (9 * 3b + 3b * 3b)) = 0
(-81 + -27b + (27b + 9b2)) = 0

Combine like terms: -27b + 27b = 0
(-81 + 0 + 9b2) = 0
(-81 + 9b2) = 0

Solving
-81 + 9b2 = 0

Solving for variable 'b'.

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

Add '81' to each side of the equation.
-81 + 81 + 9b2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 9b2 = 0 + 81
9b2 = 0 + 81

Combine like terms: 0 + 81 = 81
9b2 = 81

Divide each side by '9'.
b2 = 9

Simplifying
b2 = 9

Take the square root of each side:
b = {-3, 3}