(U-9u)(u+9u)=0

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

Simplifying
(U + -9u)(u + 9u) = 0

Combine like terms: u + 9u = 10u
(U + -9u)(10u) = 0

Remove parenthesis around (10u)
(U + -9u) * 10u = 0

Reorder the terms for easier multiplication:
10u(U + -9u) = 0
(U * 10u + -9u * 10u) = 0
(10uU + -90u2) = 0

Solving
10uU + -90u2 = 0

Solving for variable 'u'.

Factor out the Greatest Common Factor (GCF), '10u'.
10u(U + -9u) = 0

Ignore the factor 10.
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 '(U + -9u)' equal to zero and attempt to solve:

Simplifying
U + -9u = 0

Solving
U + -9u = 0

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

Add '-1U' to each side of the equation.
U + -1U + -9u = 0 + -1U

Combine like terms: U + -1U = 0
0 + -9u = 0 + -1U
-9u = 0 + -1U
Remove the zero:
-9u = -1U

Divide each side by '-9'.
u = 0.1111111111U

Simplifying
u = 0.1111111111U
Solution
u = {0, 0.1111111111U}