(5-u)(5u-4)=0

Solution for (5-u)(5u-4)=0 equation:

Simplifying
(5 + -1u)(5u + -4) = 0

Reorder the terms:
(5 + -1u)(-4 + 5u) = 0

Multiply (5 + -1u) * (-4 + 5u)
(5(-4 + 5u) + -1u * (-4 + 5u)) = 0
((-4 * 5 + 5u * 5) + -1u * (-4 + 5u)) = 0
((-20 + 25u) + -1u * (-4 + 5u)) = 0
(-20 + 25u + (-4 * -1u + 5u * -1u)) = 0
(-20 + 25u + (4u + -5u2)) = 0

Combine like terms: 25u + 4u = 29u
(-20 + 29u + -5u2) = 0

Solving
-20 + 29u + -5u2 = 0

Solving for variable 'u'.

Factor a trinomial.
(-5 + u)(4 + -5u) = 0

Subproblem 1
Set the factor '(-5 + u)' equal to zero and attempt to solve:

Simplifying
-5 + u = 0

Solving
-5 + u = 0

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

Add '5' to each side of the equation.
-5 + 5 + u = 0 + 5

Combine like terms: -5 + 5 = 0
0 + u = 0 + 5
u = 0 + 5

Combine like terms: 0 + 5 = 5
u = 5

Simplifying
u = 5
Subproblem 2
Set the factor '(4 + -5u)' equal to zero and attempt to solve:

Simplifying
4 + -5u = 0

Solving
4 + -5u = 0

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

Add '-4' to each side of the equation.
4 + -4 + -5u = 0 + -4

Combine like terms: 4 + -4 = 0
0 + -5u = 0 + -4
-5u = 0 + -4

Combine like terms: 0 + -4 = -4
-5u = -4

Divide each side by '-5'.
u = 0.8

Simplifying
u = 0.8
Solution
u = {5, 0.8}