0=x^2-9x-9

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Solution for 0=x^2-9x-9 equation:


Simplifying
0 = x2 + -9x + -9

Reorder the terms:
0 = -9 + -9x + x2

Solving
0 = -9 + -9x + x2

Solving for variable 'x'.

Combine like terms: 0 + 9 = 9
9 + 9x + -1x2 = -9 + -9x + x2 + 9 + 9x + -1x2

Reorder the terms:
9 + 9x + -1x2 = -9 + 9 + -9x + 9x + x2 + -1x2

Combine like terms: -9 + 9 = 0
9 + 9x + -1x2 = 0 + -9x + 9x + x2 + -1x2
9 + 9x + -1x2 = -9x + 9x + x2 + -1x2

Combine like terms: -9x + 9x = 0
9 + 9x + -1x2 = 0 + x2 + -1x2
9 + 9x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
9 + 9x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-9 + -9x + x2 = 0

Move the constant term to the right:

Add '9' to each side of the equation.
-9 + -9x + 9 + x2 = 0 + 9

Reorder the terms:
-9 + 9 + -9x + x2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -9x + x2 = 0 + 9
-9x + x2 = 0 + 9

Combine like terms: 0 + 9 = 9
-9x + x2 = 9

The x term is -9x.  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.
-9x + 20.25 + x2 = 9 + 20.25

Reorder the terms:
20.25 + -9x + x2 = 9 + 20.25

Combine like terms: 9 + 20.25 = 29.25
20.25 + -9x + x2 = 29.25

Factor a perfect square on the left side:
(x + -4.5)(x + -4.5) = 29.25

Calculate the square root of the right side: 5.408326913

Break this problem into two subproblems by setting 
(x + -4.5) equal to 5.408326913 and -5.408326913.

Subproblem 1

x + -4.5 = 5.408326913 Simplifying x + -4.5 = 5.408326913 Reorder the terms: -4.5 + x = 5.408326913 Solving -4.5 + x = 5.408326913 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + x = 5.408326913 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = 5.408326913 + 4.5 x = 5.408326913 + 4.5 Combine like terms: 5.408326913 + 4.5 = 9.908326913 x = 9.908326913 Simplifying x = 9.908326913

Subproblem 2

x + -4.5 = -5.408326913 Simplifying x + -4.5 = -5.408326913 Reorder the terms: -4.5 + x = -5.408326913 Solving -4.5 + x = -5.408326913 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + x = -5.408326913 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = -5.408326913 + 4.5 x = -5.408326913 + 4.5 Combine like terms: -5.408326913 + 4.5 = -0.908326913 x = -0.908326913 Simplifying x = -0.908326913

Solution

The solution to the problem is based on the solutions from the subproblems. x = {9.908326913, -0.908326913}

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