15u^5+21u^4-18u^3=0

Solution for 15u^5+21u^4-18u^3=0 equation:

Simplifying
15u5 + 21u4 + -18u3 = 0

Reorder the terms:
-18u3 + 21u4 + 15u5 = 0

Solving
-18u3 + 21u4 + 15u5 = 0

Solving for variable 'u'.

Factor out the Greatest Common Factor (GCF), '3u3'.
3u3(-6 + 7u + 5u2) = 0

Factor a trinomial.
3u3((-2 + -1u)(3 + -5u)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor 'u3' equal to zero and attempt to solve:

Simplifying
u3 = 0

Solving
u3 = 0

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

Simplifying
u3 = 0

The solution to this equation could not be determined.

This subproblem is being ignored because a solution could not be determined.
Subproblem 2
Set the factor '(-2 + -1u)' equal to zero and attempt to solve:

Simplifying
-2 + -1u = 0

Solving
-2 + -1u = 0

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

Add '2' to each side of the equation.
-2 + 2 + -1u = 0 + 2

Combine like terms: -2 + 2 = 0
0 + -1u = 0 + 2
-1u = 0 + 2

Combine like terms: 0 + 2 = 2
-1u = 2

Divide each side by '-1'.
u = -2

Simplifying
u = -2
Subproblem 3
Set the factor '(3 + -5u)' equal to zero and attempt to solve:

Simplifying
3 + -5u = 0

Solving
3 + -5u = 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 + -5u = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -5u = 0 + -3
-5u = 0 + -3

Combine like terms: 0 + -3 = -3
-5u = -3

Divide each side by '-5'.
u = 0.6

Simplifying
u = 0.6
Solution
u = {-2, 0.6}