(9+u)(4u+1)=0

Solution for (9+u)(4u+1)=0 equation:

Simplifying
(9 + u)(4u + 1) = 0

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

Multiply (9 + u) * (1 + 4u)
(9(1 + 4u) + u(1 + 4u)) = 0
((1 * 9 + 4u * 9) + u(1 + 4u)) = 0
((9 + 36u) + u(1 + 4u)) = 0
(9 + 36u + (1 * u + 4u * u)) = 0
(9 + 36u + (1u + 4u2)) = 0

Combine like terms: 36u + 1u = 37u
(9 + 37u + 4u2) = 0

Solving
9 + 37u + 4u2 = 0

Solving for variable 'u'.

Factor a trinomial.
(9 + u)(1 + 4u) = 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 '(1 + 4u)' equal to zero and attempt to solve:

Simplifying
1 + 4u = 0

Solving
1 + 4u = 0

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

Add '-1' to each side of the equation.
1 + -1 + 4u = 0 + -1

Combine like terms: 1 + -1 = 0
0 + 4u = 0 + -1
4u = 0 + -1

Combine like terms: 0 + -1 = -1
4u = -1

Divide each side by '4'.
u = -0.25

Simplifying
u = -0.25
Solution
u = {-9, -0.25}