(9u^2-9u-6)+(-5u^2+4u+8)-(-7u^2+9u+7)=

Solution for (9u^2-9u-6)+(-5u^2+4u+8)-(-7u^2+9u+7)= equation:

Simplifying
(9u2 + -9u + -6) + (-5u2 + 4u + 8) + -1(-7u2 + 9u + 7) = 0

Reorder the terms:
(-6 + -9u + 9u2) + (-5u2 + 4u + 8) + -1(-7u2 + 9u + 7) = 0

Remove parenthesis around (-6 + -9u + 9u2)
-6 + -9u + 9u2 + (-5u2 + 4u + 8) + -1(-7u2 + 9u + 7) = 0

Reorder the terms:
-6 + -9u + 9u2 + (8 + 4u + -5u2) + -1(-7u2 + 9u + 7) = 0

Remove parenthesis around (8 + 4u + -5u2)
-6 + -9u + 9u2 + 8 + 4u + -5u2 + -1(-7u2 + 9u + 7) = 0

Reorder the terms:
-6 + -9u + 9u2 + 8 + 4u + -5u2 + -1(7 + 9u + -7u2) = 0
-6 + -9u + 9u2 + 8 + 4u + -5u2 + (7 * -1 + 9u * -1 + -7u2 * -1) = 0
-6 + -9u + 9u2 + 8 + 4u + -5u2 + (-7 + -9u + 7u2) = 0

Reorder the terms:
-6 + 8 + -7 + -9u + 4u + -9u + 9u2 + -5u2 + 7u2 = 0

Combine like terms: -6 + 8 = 2
2 + -7 + -9u + 4u + -9u + 9u2 + -5u2 + 7u2 = 0

Combine like terms: 2 + -7 = -5
-5 + -9u + 4u + -9u + 9u2 + -5u2 + 7u2 = 0

Combine like terms: -9u + 4u = -5u
-5 + -5u + -9u + 9u2 + -5u2 + 7u2 = 0

Combine like terms: -5u + -9u = -14u
-5 + -14u + 9u2 + -5u2 + 7u2 = 0

Combine like terms: 9u2 + -5u2 = 4u2
-5 + -14u + 4u2 + 7u2 = 0

Combine like terms: 4u2 + 7u2 = 11u2
-5 + -14u + 11u2 = 0

Solving
-5 + -14u + 11u2 = 0

Solving for variable 'u'.

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

Divide each side by '11'.
-0.4545454545 + -1.272727273u + u2 = 0

Move the constant term to the right:

Add '0.4545454545' to each side of the equation.
-0.4545454545 + -1.272727273u + 0.4545454545 + u2 = 0 + 0.4545454545

Reorder the terms:
-0.4545454545 + 0.4545454545 + -1.272727273u + u2 = 0 + 0.4545454545

Combine like terms: -0.4545454545 + 0.4545454545 = 0.0000000000
0.0000000000 + -1.272727273u + u2 = 0 + 0.4545454545
-1.272727273u + u2 = 0 + 0.4545454545

Combine like terms: 0 + 0.4545454545 = 0.4545454545
-1.272727273u + u2 = 0.4545454545

The u term is -1.272727273u.  Take half its coefficient (-0.6363636365).
Square it (0.4049586779) and add it to both sides.

Add '0.4049586779' to each side of the equation.
-1.272727273u + 0.4049586779 + u2 = 0.4545454545 + 0.4049586779

Reorder the terms:
0.4049586779 + -1.272727273u + u2 = 0.4545454545 + 0.4049586779

Combine like terms: 0.4545454545 + 0.4049586779 = 0.8595041324
0.4049586779 + -1.272727273u + u2 = 0.8595041324

Factor a perfect square on the left side:
(u + -0.6363636365)(u + -0.6363636365) = 0.8595041324

Calculate the square root of the right side: 0.927094457

Break this problem into two subproblems by setting 
(u + -0.6363636365) equal to 0.927094457 and -0.927094457.

Subproblem 1
u + -0.6363636365 = 0.927094457

Simplifying
u + -0.6363636365 = 0.927094457

Reorder the terms:
-0.6363636365 + u = 0.927094457

Solving
-0.6363636365 + u = 0.927094457

Solving for variable 'u'.

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

Add '0.6363636365' to each side of the equation.
-0.6363636365 + 0.6363636365 + u = 0.927094457 + 0.6363636365

Combine like terms: -0.6363636365 + 0.6363636365 = 0.0000000000
0.0000000000 + u = 0.927094457 + 0.6363636365
u = 0.927094457 + 0.6363636365

Combine like terms: 0.927094457 + 0.6363636365 = 1.5634580935
u = 1.5634580935

Simplifying
u = 1.5634580935

Subproblem 2
u + -0.6363636365 = -0.927094457

Simplifying
u + -0.6363636365 = -0.927094457

Reorder the terms:
-0.6363636365 + u = -0.927094457

Solving
-0.6363636365 + u = -0.927094457

Solving for variable 'u'.

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

Add '0.6363636365' to each side of the equation.
-0.6363636365 + 0.6363636365 + u = -0.927094457 + 0.6363636365

Combine like terms: -0.6363636365 + 0.6363636365 = 0.0000000000
0.0000000000 + u = -0.927094457 + 0.6363636365
u = -0.927094457 + 0.6363636365

Combine like terms: -0.927094457 + 0.6363636365 = -0.2907308205
u = -0.2907308205

Simplifying
u = -0.2907308205

Solution
The solution to the problem is based on the solutions
from the subproblems.
u = {1.5634580935, -0.2907308205}