(2r+6)(2r-6)=

Solution for (2r+6)(2r-6)= equation:

Simplifying
(2r + 6)(2r + -6) = 0

Reorder the terms:
(6 + 2r)(2r + -6) = 0

Reorder the terms:
(6 + 2r)(-6 + 2r) = 0

Multiply (6 + 2r) * (-6 + 2r)
(6(-6 + 2r) + 2r * (-6 + 2r)) = 0
((-6 * 6 + 2r * 6) + 2r * (-6 + 2r)) = 0
((-36 + 12r) + 2r * (-6 + 2r)) = 0
(-36 + 12r + (-6 * 2r + 2r * 2r)) = 0
(-36 + 12r + (-12r + 4r2)) = 0

Combine like terms: 12r + -12r = 0
(-36 + 0 + 4r2) = 0
(-36 + 4r2) = 0

Solving
-36 + 4r2 = 0

Solving for variable 'r'.

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

Add '36' to each side of the equation.
-36 + 36 + 4r2 = 0 + 36

Combine like terms: -36 + 36 = 0
0 + 4r2 = 0 + 36
4r2 = 0 + 36

Combine like terms: 0 + 36 = 36
4r2 = 36

Divide each side by '4'.
r2 = 9

Simplifying
r2 = 9

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