(3-u)(3u-7)=0

Solution for (3-u)(3u-7)=0 equation:

Simplifying
(3 + -1u)(3u + -7) = 0

Reorder the terms:
(3 + -1u)(-7 + 3u) = 0

Multiply (3 + -1u) * (-7 + 3u)
(3(-7 + 3u) + -1u * (-7 + 3u)) = 0
((-7 * 3 + 3u * 3) + -1u * (-7 + 3u)) = 0
((-21 + 9u) + -1u * (-7 + 3u)) = 0
(-21 + 9u + (-7 * -1u + 3u * -1u)) = 0
(-21 + 9u + (7u + -3u2)) = 0

Combine like terms: 9u + 7u = 16u
(-21 + 16u + -3u2) = 0

Solving
-21 + 16u + -3u2 = 0

Solving for variable 'u'.

Factor a trinomial.
(-3 + u)(7 + -3u) = 0

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

Simplifying
-3 + u = 0

Solving
-3 + u = 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 + u = 0 + 3

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

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

Simplifying
u = 3
Subproblem 2
Set the factor '(7 + -3u)' equal to zero and attempt to solve:

Simplifying
7 + -3u = 0

Solving
7 + -3u = 0

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

Add '-7' to each side of the equation.
7 + -7 + -3u = 0 + -7

Combine like terms: 7 + -7 = 0
0 + -3u = 0 + -7
-3u = 0 + -7

Combine like terms: 0 + -7 = -7
-3u = -7

Divide each side by '-3'.
u = 2.333333333

Simplifying
u = 2.333333333
Solution
u = {3, 2.333333333}