(5f-8)(8+5f)=

Solution for (5f-8)(8+5f)= equation:

Simplifying
(5f + -8)(8 + 5f) = 0

Reorder the terms:
(-8 + 5f)(8 + 5f) = 0

Multiply (-8 + 5f) * (8 + 5f)
(-8(8 + 5f) + 5f * (8 + 5f)) = 0
((8 * -8 + 5f * -8) + 5f * (8 + 5f)) = 0
((-64 + -40f) + 5f * (8 + 5f)) = 0
(-64 + -40f + (8 * 5f + 5f * 5f)) = 0
(-64 + -40f + (40f + 25f2)) = 0

Combine like terms: -40f + 40f = 0
(-64 + 0 + 25f2) = 0
(-64 + 25f2) = 0

Solving
-64 + 25f2 = 0

Solving for variable 'f'.

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

Add '64' to each side of the equation.
-64 + 64 + 25f2 = 0 + 64

Combine like terms: -64 + 64 = 0
0 + 25f2 = 0 + 64
25f2 = 0 + 64

Combine like terms: 0 + 64 = 64
25f2 = 64

Divide each side by '25'.
f2 = 2.56

Simplifying
f2 = 2.56

Take the square root of each side:
f = {-1.6, 1.6}