(5b+4)(5b-4)=0

Solution for (5b+4)(5b-4)=0 equation:

Simplifying
(5b + 4)(5b + -4) = 0

Reorder the terms:
(4 + 5b)(5b + -4) = 0

Reorder the terms:
(4 + 5b)(-4 + 5b) = 0

Multiply (4 + 5b) * (-4 + 5b)
(4(-4 + 5b) + 5b * (-4 + 5b)) = 0
((-4 * 4 + 5b * 4) + 5b * (-4 + 5b)) = 0
((-16 + 20b) + 5b * (-4 + 5b)) = 0
(-16 + 20b + (-4 * 5b + 5b * 5b)) = 0
(-16 + 20b + (-20b + 25b2)) = 0

Combine like terms: 20b + -20b = 0
(-16 + 0 + 25b2) = 0
(-16 + 25b2) = 0

Solving
-16 + 25b2 = 0

Solving for variable 'b'.

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

Add '16' to each side of the equation.
-16 + 16 + 25b2 = 0 + 16

Combine like terms: -16 + 16 = 0
0 + 25b2 = 0 + 16
25b2 = 0 + 16

Combine like terms: 0 + 16 = 16
25b2 = 16

Divide each side by '25'.
b2 = 0.64

Simplifying
b2 = 0.64

Take the square root of each side:
b = {-0.8, 0.8}