(-2u^2-9u-5)+(9u^2-3u+3)-(3u^2+6u-4)=

Solution for (-2u^2-9u-5)+(9u^2-3u+3)-(3u^2+6u-4)= equation:

Simplifying
(-2u2 + -9u + -5) + (9u2 + -3u + 3) + -1(3u2 + 6u + -4) = 0

Reorder the terms:
(-5 + -9u + -2u2) + (9u2 + -3u + 3) + -1(3u2 + 6u + -4) = 0

Remove parenthesis around (-5 + -9u + -2u2)
-5 + -9u + -2u2 + (9u2 + -3u + 3) + -1(3u2 + 6u + -4) = 0

Reorder the terms:
-5 + -9u + -2u2 + (3 + -3u + 9u2) + -1(3u2 + 6u + -4) = 0

Remove parenthesis around (3 + -3u + 9u2)
-5 + -9u + -2u2 + 3 + -3u + 9u2 + -1(3u2 + 6u + -4) = 0

Reorder the terms:
-5 + -9u + -2u2 + 3 + -3u + 9u2 + -1(-4 + 6u + 3u2) = 0
-5 + -9u + -2u2 + 3 + -3u + 9u2 + (-4 * -1 + 6u * -1 + 3u2 * -1) = 0
-5 + -9u + -2u2 + 3 + -3u + 9u2 + (4 + -6u + -3u2) = 0

Reorder the terms:
-5 + 3 + 4 + -9u + -3u + -6u + -2u2 + 9u2 + -3u2 = 0

Combine like terms: -5 + 3 = -2
-2 + 4 + -9u + -3u + -6u + -2u2 + 9u2 + -3u2 = 0

Combine like terms: -2 + 4 = 2
2 + -9u + -3u + -6u + -2u2 + 9u2 + -3u2 = 0

Combine like terms: -9u + -3u = -12u
2 + -12u + -6u + -2u2 + 9u2 + -3u2 = 0

Combine like terms: -12u + -6u = -18u
2 + -18u + -2u2 + 9u2 + -3u2 = 0

Combine like terms: -2u2 + 9u2 = 7u2
2 + -18u + 7u2 + -3u2 = 0

Combine like terms: 7u2 + -3u2 = 4u2
2 + -18u + 4u2 = 0

Solving
2 + -18u + 4u2 = 0

Solving for variable 'u'.

Factor out the Greatest Common Factor (GCF), '2'.
2(1 + -9u + 2u2) = 0

Ignore the factor 2.
Subproblem 1
Set the factor '(1 + -9u + 2u2)' equal to zero and attempt to solve:

Simplifying
1 + -9u + 2u2 = 0

Solving
1 + -9u + 2u2 = 0

Begin completing the square.  Divide all terms by
2 the coefficient of the squared term: 

Divide each side by '2'.
0.5 + -4.5u + u2 = 0

Move the constant term to the right:

Add '-0.5' to each side of the equation.
0.5 + -4.5u + -0.5 + u2 = 0 + -0.5

Reorder the terms:
0.5 + -0.5 + -4.5u + u2 = 0 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + -4.5u + u2 = 0 + -0.5
-4.5u + u2 = 0 + -0.5

Combine like terms: 0 + -0.5 = -0.5
-4.5u + u2 = -0.5

The u term is -4.5u.  Take half its coefficient (-2.25).
Square it (5.0625) and add it to both sides.

Add '5.0625' to each side of the equation.
-4.5u + 5.0625 + u2 = -0.5 + 5.0625

Reorder the terms:
5.0625 + -4.5u + u2 = -0.5 + 5.0625

Combine like terms: -0.5 + 5.0625 = 4.5625
5.0625 + -4.5u + u2 = 4.5625

Factor a perfect square on the left side:
(u + -2.25)(u + -2.25) = 4.5625

Calculate the square root of the right side: 2.136000936

Break this problem into two subproblems by setting 
(u + -2.25) equal to 2.136000936 and -2.136000936.

Subproblem 1
u + -2.25 = 2.136000936

Simplifying
u + -2.25 = 2.136000936

Reorder the terms:
-2.25 + u = 2.136000936

Solving
-2.25 + u = 2.136000936

Solving for variable 'u'.

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

Add '2.25' to each side of the equation.
-2.25 + 2.25 + u = 2.136000936 + 2.25

Combine like terms: -2.25 + 2.25 = 0.00
0.00 + u = 2.136000936 + 2.25
u = 2.136000936 + 2.25

Combine like terms: 2.136000936 + 2.25 = 4.386000936
u = 4.386000936

Simplifying
u = 4.386000936

Subproblem 2
u + -2.25 = -2.136000936

Simplifying
u + -2.25 = -2.136000936

Reorder the terms:
-2.25 + u = -2.136000936

Solving
-2.25 + u = -2.136000936

Solving for variable 'u'.

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

Add '2.25' to each side of the equation.
-2.25 + 2.25 + u = -2.136000936 + 2.25

Combine like terms: -2.25 + 2.25 = 0.00
0.00 + u = -2.136000936 + 2.25
u = -2.136000936 + 2.25

Combine like terms: -2.136000936 + 2.25 = 0.113999064
u = 0.113999064

Simplifying
u = 0.113999064

Solution
The solution to the problem is based on the solutions
from the subproblems.
u = {4.386000936, 0.113999064}
Solution
u = {4.386000936, 0.113999064}