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

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

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

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

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

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

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

Solving
-4 + 25r2 = 0

Solving for variable 'r'.

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

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

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

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

Divide each side by '25'.
r2 = 0.16

Simplifying
r2 = 0.16

Take the square root of each side:
r = {-0.4, 0.4}