(9+u)(5u+4)=0

Solution for (9+u)(5u+4)=0 equation:

Simplifying
(9 + u)(5u + 4) = 0

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

Multiply (9 + u) * (4 + 5u)
(9(4 + 5u) + u(4 + 5u)) = 0
((4 * 9 + 5u * 9) + u(4 + 5u)) = 0
((36 + 45u) + u(4 + 5u)) = 0
(36 + 45u + (4 * u + 5u * u)) = 0
(36 + 45u + (4u + 5u2)) = 0

Combine like terms: 45u + 4u = 49u
(36 + 49u + 5u2) = 0

Solving
36 + 49u + 5u2 = 0

Solving for variable 'u'.

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

Subproblem 1
Set the factor '(9 + u)' equal to zero and attempt to solve:

Simplifying
9 + u = 0

Solving
9 + u = 0

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

Add '-9' to each side of the equation.
9 + -9 + u = 0 + -9

Combine like terms: 9 + -9 = 0
0 + u = 0 + -9
u = 0 + -9

Combine like terms: 0 + -9 = -9
u = -9

Simplifying
u = -9
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 = {-9, -0.8}