0=u^2-4u

Solution for 0=u^2-4u equation:

Simplifying
0 = u2 + -4u

Reorder the terms:
0 = -4u + u2

Solving
0 = -4u + u2

Solving for variable 'u'.
Remove the zero:
4u + -1u2 = -4u + u2 + 4u + -1u2

Reorder the terms:
4u + -1u2 = -4u + 4u + u2 + -1u2

Combine like terms: -4u + 4u = 0
4u + -1u2 = 0 + u2 + -1u2
4u + -1u2 = u2 + -1u2

Combine like terms: u2 + -1u2 = 0
4u + -1u2 = 0

Factor out the Greatest Common Factor (GCF), 'u'.
u(4 + -1u) = 0

Subproblem 1
Set the factor 'u' equal to zero and attempt to solve:

Simplifying
u = 0

Solving
u = 0

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

Simplifying
u = 0
Subproblem 2
Set the factor '(4 + -1u)' equal to zero and attempt to solve:

Simplifying
4 + -1u = 0

Solving
4 + -1u = 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 + -1u = 0 + -4

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

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

Divide each side by '-1'.
u = 4

Simplifying
u = 4
Solution
u = {0, 4}