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

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

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

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

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

Multiply (4 + 5a) * (-4 + 5a)
(4(-4 + 5a) + 5a * (-4 + 5a)) = 0
((-4 * 4 + 5a * 4) + 5a * (-4 + 5a)) = 0
((-16 + 20a) + 5a * (-4 + 5a)) = 0
(-16 + 20a + (-4 * 5a + 5a * 5a)) = 0
(-16 + 20a + (-20a + 25a2)) = 0

Combine like terms: 20a + -20a = 0
(-16 + 0 + 25a2) = 0
(-16 + 25a2) = 0

Solving
-16 + 25a2 = 0

Solving for variable 'a'.

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

Add '16' to each side of the equation.
-16 + 16 + 25a2 = 0 + 16

Combine like terms: -16 + 16 = 0
0 + 25a2 = 0 + 16
25a2 = 0 + 16

Combine like terms: 0 + 16 = 16
25a2 = 16

Divide each side by '25'.
a2 = 0.64

Simplifying
a2 = 0.64

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