u^2-9u-4=0

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Solution for u^2-9u-4=0 equation: 


Simplifying
u2 + -9u + -4 = 0

Reorder the terms:
-4 + -9u + u2 = 0

Solving
-4 + -9u + u2 = 0

Solving for variable 'u'.

Begin completing the square.

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + -9u + 4 + u2 = 0 + 4

Reorder the terms:
-4 + 4 + -9u + u2 = 0 + 4

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

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

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 = 4 + 20.25

Reorder the terms:
20.25 + -9u + u2 = 4 + 20.25

Combine like terms: 4 + 20.25 = 24.25
20.25 + -9u + u2 = 24.25

Factor a perfect square on the left side:
(u + -4.5)(u + -4.5) = 24.25

Calculate the square root of the right side: 4.924428901

Break this problem into two subproblems by setting 
(u + -4.5) equal to 4.924428901 and -4.924428901.


Subproblem 1
u + -4.5 = 4.924428901

Simplifying
u + -4.5 = 4.924428901

Reorder the terms:
-4.5 + u = 4.924428901

Solving
-4.5 + u = 4.924428901

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 = 4.924428901 + 4.5

Combine like terms: -4.5 + 4.5 = 0.0
0.0 + u = 4.924428901 + 4.5
u = 4.924428901 + 4.5

Combine like terms: 4.924428901 + 4.5 = 9.424428901
u = 9.424428901

Simplifying
u = 9.424428901


Subproblem 2
u + -4.5 = -4.924428901

Simplifying
u + -4.5 = -4.924428901

Reorder the terms:
-4.5 + u = -4.924428901

Solving
-4.5 + u = -4.924428901

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 = -4.924428901 + 4.5

Combine like terms: -4.5 + 4.5 = 0.0
0.0 + u = -4.924428901 + 4.5
u = -4.924428901 + 4.5

Combine like terms: -4.924428901 + 4.5 = -0.424428901
u = -0.424428901

Simplifying
u = -0.424428901


Solution
The solution to the problem is based on the solutions
from the subproblems.
u = {9.424428901, -0.424428901}

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