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

Solution for (3-u)(4u+5)=0 equation:

Simplifying
(3 + -1u)(4u + 5) = 0

Reorder the terms:
(3 + -1u)(5 + 4u) = 0

Multiply (3 + -1u) * (5 + 4u)
(3(5 + 4u) + -1u * (5 + 4u)) = 0
((5 * 3 + 4u * 3) + -1u * (5 + 4u)) = 0
((15 + 12u) + -1u * (5 + 4u)) = 0
(15 + 12u + (5 * -1u + 4u * -1u)) = 0
(15 + 12u + (-5u + -4u2)) = 0

Combine like terms: 12u + -5u = 7u
(15 + 7u + -4u2) = 0

Solving
15 + 7u + -4u2 = 0

Solving for variable 'u'.

Factor a trinomial.
(3 + -1u)(5 + 4u) = 0

Subproblem 1
Set the factor '(3 + -1u)' equal to zero and attempt to solve:

Simplifying
3 + -1u = 0

Solving
3 + -1u = 0

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

Add '-3' to each side of the equation.
3 + -3 + -1u = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -1u = 0 + -3
-1u = 0 + -3

Combine like terms: 0 + -3 = -3
-1u = -3

Divide each side by '-1'.
u = 3

Simplifying
u = 3
Subproblem 2
Set the factor '(5 + 4u)' equal to zero and attempt to solve:

Simplifying
5 + 4u = 0

Solving
5 + 4u = 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 + 4u = 0 + -5

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

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

Divide each side by '4'.
u = -1.25

Simplifying
u = -1.25
Solution
u = {3, -1.25}