(3-u)(5u+9)=0

Solution for (3-u)(5u+9)=0 equation:

Simplifying
(3 + -1u)(5u + 9) = 0

Reorder the terms:
(3 + -1u)(9 + 5u) = 0

Multiply (3 + -1u) * (9 + 5u)
(3(9 + 5u) + -1u * (9 + 5u)) = 0
((9 * 3 + 5u * 3) + -1u * (9 + 5u)) = 0
((27 + 15u) + -1u * (9 + 5u)) = 0
(27 + 15u + (9 * -1u + 5u * -1u)) = 0
(27 + 15u + (-9u + -5u2)) = 0

Combine like terms: 15u + -9u = 6u
(27 + 6u + -5u2) = 0

Solving
27 + 6u + -5u2 = 0

Solving for variable 'u'.

Factor a trinomial.
(3 + -1u)(9 + 5u) = 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 '(9 + 5u)' equal to zero and attempt to solve:

Simplifying
9 + 5u = 0

Solving
9 + 5u = 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 + 5u = 0 + -9

Combine like terms: 9 + -9 = 0
0 + 5u = 0 + -9
5u = 0 + -9

Combine like terms: 0 + -9 = -9
5u = -9

Divide each side by '5'.
u = -1.8

Simplifying
u = -1.8
Solution
u = {3, -1.8}