(8u^2-7u+9)+(3u^2-9u-9)-(7u^2-2u-1)=

Solution for (8u^2-7u+9)+(3u^2-9u-9)-(7u^2-2u-1)= equation:

Simplifying
(8u2 + -7u + 9) + (3u2 + -9u + -9) + -1(7u2 + -2u + -1) = 0

Reorder the terms:
(9 + -7u + 8u2) + (3u2 + -9u + -9) + -1(7u2 + -2u + -1) = 0

Remove parenthesis around (9 + -7u + 8u2)
9 + -7u + 8u2 + (3u2 + -9u + -9) + -1(7u2 + -2u + -1) = 0

Reorder the terms:
9 + -7u + 8u2 + (-9 + -9u + 3u2) + -1(7u2 + -2u + -1) = 0

Remove parenthesis around (-9 + -9u + 3u2)
9 + -7u + 8u2 + -9 + -9u + 3u2 + -1(7u2 + -2u + -1) = 0

Reorder the terms:
9 + -7u + 8u2 + -9 + -9u + 3u2 + -1(-1 + -2u + 7u2) = 0
9 + -7u + 8u2 + -9 + -9u + 3u2 + (-1 * -1 + -2u * -1 + 7u2 * -1) = 0
9 + -7u + 8u2 + -9 + -9u + 3u2 + (1 + 2u + -7u2) = 0

Reorder the terms:
9 + -9 + 1 + -7u + -9u + 2u + 8u2 + 3u2 + -7u2 = 0

Combine like terms: 9 + -9 = 0
0 + 1 + -7u + -9u + 2u + 8u2 + 3u2 + -7u2 = 0
1 + -7u + -9u + 2u + 8u2 + 3u2 + -7u2 = 0

Combine like terms: -7u + -9u = -16u
1 + -16u + 2u + 8u2 + 3u2 + -7u2 = 0

Combine like terms: -16u + 2u = -14u
1 + -14u + 8u2 + 3u2 + -7u2 = 0

Combine like terms: 8u2 + 3u2 = 11u2
1 + -14u + 11u2 + -7u2 = 0

Combine like terms: 11u2 + -7u2 = 4u2
1 + -14u + 4u2 = 0

Solving
1 + -14u + 4u2 = 0

Solving for variable 'u'.

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

Divide each side by '4'.
0.25 + -3.5u + u2 = 0

Move the constant term to the right:

Add '-0.25' to each side of the equation.
0.25 + -3.5u + -0.25 + u2 = 0 + -0.25

Reorder the terms:
0.25 + -0.25 + -3.5u + u2 = 0 + -0.25

Combine like terms: 0.25 + -0.25 = 0.00
0.00 + -3.5u + u2 = 0 + -0.25
-3.5u + u2 = 0 + -0.25

Combine like terms: 0 + -0.25 = -0.25
-3.5u + u2 = -0.25

The u term is -3.5u.  Take half its coefficient (-1.75).
Square it (3.0625) and add it to both sides.

Add '3.0625' to each side of the equation.
-3.5u + 3.0625 + u2 = -0.25 + 3.0625

Reorder the terms:
3.0625 + -3.5u + u2 = -0.25 + 3.0625

Combine like terms: -0.25 + 3.0625 = 2.8125
3.0625 + -3.5u + u2 = 2.8125

Factor a perfect square on the left side:
(u + -1.75)(u + -1.75) = 2.8125

Calculate the square root of the right side: 1.677050983

Break this problem into two subproblems by setting 
(u + -1.75) equal to 1.677050983 and -1.677050983.

Subproblem 1
u + -1.75 = 1.677050983

Simplifying
u + -1.75 = 1.677050983

Reorder the terms:
-1.75 + u = 1.677050983

Solving
-1.75 + u = 1.677050983

Solving for variable 'u'.

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

Add '1.75' to each side of the equation.
-1.75 + 1.75 + u = 1.677050983 + 1.75

Combine like terms: -1.75 + 1.75 = 0.00
0.00 + u = 1.677050983 + 1.75
u = 1.677050983 + 1.75

Combine like terms: 1.677050983 + 1.75 = 3.427050983
u = 3.427050983

Simplifying
u = 3.427050983

Subproblem 2
u + -1.75 = -1.677050983

Simplifying
u + -1.75 = -1.677050983

Reorder the terms:
-1.75 + u = -1.677050983

Solving
-1.75 + u = -1.677050983

Solving for variable 'u'.

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

Add '1.75' to each side of the equation.
-1.75 + 1.75 + u = -1.677050983 + 1.75

Combine like terms: -1.75 + 1.75 = 0.00
0.00 + u = -1.677050983 + 1.75
u = -1.677050983 + 1.75

Combine like terms: -1.677050983 + 1.75 = 0.072949017
u = 0.072949017

Simplifying
u = 0.072949017

Solution
The solution to the problem is based on the solutions
from the subproblems.
u = {3.427050983, 0.072949017}