u^2+9u+7=0

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Solution for u^2+9u+7=0 equation: 


Simplifying
u2 + 9u + 7 = 0

Reorder the terms:
7 + 9u + u2 = 0

Solving
7 + 9u + u2 = 0

Solving for variable 'u'.

Begin completing the square.

Move the constant term to the right:

Add '-7' to each side of the equation.
7 + 9u + -7 + u2 = 0 + -7

Reorder the terms:
7 + -7 + 9u + u2 = 0 + -7

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

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

The u term is 9u.  Take half its coefficient (4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
9u + 20.25 + u2 = -7 + 20.25

Reorder the terms:
20.25 + 9u + u2 = -7 + 20.25

Combine like terms: -7 + 20.25 = 13.25
20.25 + 9u + u2 = 13.25

Factor a perfect square on the left side:
(u + 4.5)(u + 4.5) = 13.25

Calculate the square root of the right side: 3.640054945

Break this problem into two subproblems by setting 
(u + 4.5) equal to 3.640054945 and -3.640054945.


Subproblem 1
u + 4.5 = 3.640054945

Simplifying
u + 4.5 = 3.640054945

Reorder the terms:
4.5 + u = 3.640054945

Solving
4.5 + u = 3.640054945

Solving for variable 'u'.

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

Add '-4.5' to each side of the equation.
4.5 + -4.5 + u = 3.640054945 + -4.5

Combine like terms: 4.5 + -4.5 = 0.0
0.0 + u = 3.640054945 + -4.5
u = 3.640054945 + -4.5

Combine like terms: 3.640054945 + -4.5 = -0.859945055
u = -0.859945055

Simplifying
u = -0.859945055


Subproblem 2
u + 4.5 = -3.640054945

Simplifying
u + 4.5 = -3.640054945

Reorder the terms:
4.5 + u = -3.640054945

Solving
4.5 + u = -3.640054945

Solving for variable 'u'.

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

Add '-4.5' to each side of the equation.
4.5 + -4.5 + u = -3.640054945 + -4.5

Combine like terms: 4.5 + -4.5 = 0.0
0.0 + u = -3.640054945 + -4.5
u = -3.640054945 + -4.5

Combine like terms: -3.640054945 + -4.5 = -8.140054945
u = -8.140054945

Simplifying
u = -8.140054945


Solution
The solution to the problem is based on the solutions
from the subproblems.
u = {-0.859945055, -8.140054945}

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