(3l+9)(3l-9)=0

Solution for (3l+9)(3l-9)=0 equation:

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

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

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

Multiply (9 + 3l) * (-9 + 3l)
(9(-9 + 3l) + 3l * (-9 + 3l)) = 0
((-9 * 9 + 3l * 9) + 3l * (-9 + 3l)) = 0
((-81 + 27l) + 3l * (-9 + 3l)) = 0
(-81 + 27l + (-9 * 3l + 3l * 3l)) = 0
(-81 + 27l + (-27l + 9l2)) = 0

Combine like terms: 27l + -27l = 0
(-81 + 0 + 9l2) = 0
(-81 + 9l2) = 0

Solving
-81 + 9l2 = 0

Solving for variable 'l'.

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

Add '81' to each side of the equation.
-81 + 81 + 9l2 = 0 + 81

Combine like terms: -81 + 81 = 0
0 + 9l2 = 0 + 81
9l2 = 0 + 81

Combine like terms: 0 + 81 = 81
9l2 = 81

Divide each side by '9'.
l2 = 9

Simplifying
l2 = 9

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