(2r+5)(2r-5)=

Solution for (2r+5)(2r-5)= equation:

Simplifying
(2r + 5)(2r + -5) = 0

Reorder the terms:
(5 + 2r)(2r + -5) = 0

Reorder the terms:
(5 + 2r)(-5 + 2r) = 0

Multiply (5 + 2r) * (-5 + 2r)
(5(-5 + 2r) + 2r * (-5 + 2r)) = 0
((-5 * 5 + 2r * 5) + 2r * (-5 + 2r)) = 0
((-25 + 10r) + 2r * (-5 + 2r)) = 0
(-25 + 10r + (-5 * 2r + 2r * 2r)) = 0
(-25 + 10r + (-10r + 4r2)) = 0

Combine like terms: 10r + -10r = 0
(-25 + 0 + 4r2) = 0
(-25 + 4r2) = 0

Solving
-25 + 4r2 = 0

Solving for variable 'r'.

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

Add '25' to each side of the equation.
-25 + 25 + 4r2 = 0 + 25

Combine like terms: -25 + 25 = 0
0 + 4r2 = 0 + 25
4r2 = 0 + 25

Combine like terms: 0 + 25 = 25
4r2 = 25

Divide each side by '4'.
r2 = 6.25

Simplifying
r2 = 6.25

Take the square root of each side:
r = {-2.5, 2.5}