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

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

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

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

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

Multiply (5d + 2r) * (-5d + 2r)
(5d * (-5d + 2r) + 2r * (-5d + 2r)) = 0
((-5d * 5d + 2r * 5d) + 2r * (-5d + 2r)) = 0

Reorder the terms:
((10dr + -25d2) + 2r * (-5d + 2r)) = 0
((10dr + -25d2) + 2r * (-5d + 2r)) = 0
(10dr + -25d2 + (-5d * 2r + 2r * 2r)) = 0
(10dr + -25d2 + (-10dr + 4r2)) = 0

Reorder the terms:
(10dr + -10dr + -25d2 + 4r2) = 0

Combine like terms: 10dr + -10dr = 0
(0 + -25d2 + 4r2) = 0
(-25d2 + 4r2) = 0

Solving
-25d2 + 4r2 = 0

Solving for variable 'd'.

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

Add '-4r2' to each side of the equation.
-25d2 + 4r2 + -4r2 = 0 + -4r2

Combine like terms: 4r2 + -4r2 = 0
-25d2 + 0 = 0 + -4r2
-25d2 = 0 + -4r2
Remove the zero:
-25d2 = -4r2

Divide each side by '-25'.
d2 = 0.16r2

Simplifying
d2 = 0.16r2

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