(5r+7)(5r-7)=

Solution for (5r+7)(5r-7)= equation:

Simplifying
(5r + 7)(5r + -7) = 0

Reorder the terms:
(7 + 5r)(5r + -7) = 0

Reorder the terms:
(7 + 5r)(-7 + 5r) = 0

Multiply (7 + 5r) * (-7 + 5r)
(7(-7 + 5r) + 5r * (-7 + 5r)) = 0
((-7 * 7 + 5r * 7) + 5r * (-7 + 5r)) = 0
((-49 + 35r) + 5r * (-7 + 5r)) = 0
(-49 + 35r + (-7 * 5r + 5r * 5r)) = 0
(-49 + 35r + (-35r + 25r2)) = 0

Combine like terms: 35r + -35r = 0
(-49 + 0 + 25r2) = 0
(-49 + 25r2) = 0

Solving
-49 + 25r2 = 0

Solving for variable 'r'.

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

Add '49' to each side of the equation.
-49 + 49 + 25r2 = 0 + 49

Combine like terms: -49 + 49 = 0
0 + 25r2 = 0 + 49
25r2 = 0 + 49

Combine like terms: 0 + 49 = 49
25r2 = 49

Divide each side by '25'.
r2 = 1.96

Simplifying
r2 = 1.96

Take the square root of each side:
r = {-1.4, 1.4}