x^2-12x-9=0

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Solution for x^2-12x-9=0 equation:


Simplifying
x2 + -12x + -9 = 0

Reorder the terms:
-9 + -12x + x2 = 0

Solving
-9 + -12x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '9' to each side of the equation.
-9 + -12x + 9 + x2 = 0 + 9

Reorder the terms:
-9 + 9 + -12x + x2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -12x + x2 = 0 + 9
-12x + x2 = 0 + 9

Combine like terms: 0 + 9 = 9
-12x + x2 = 9

The x term is -12x.  Take half its coefficient (-6).
Square it (36) and add it to both sides.

Add '36' to each side of the equation.
-12x + 36 + x2 = 9 + 36

Reorder the terms:
36 + -12x + x2 = 9 + 36

Combine like terms: 9 + 36 = 45
36 + -12x + x2 = 45

Factor a perfect square on the left side:
(x + -6)(x + -6) = 45

Calculate the square root of the right side: 6.708203933

Break this problem into two subproblems by setting 
(x + -6) equal to 6.708203933 and -6.708203933.

Subproblem 1

x + -6 = 6.708203933 Simplifying x + -6 = 6.708203933 Reorder the terms: -6 + x = 6.708203933 Solving -6 + x = 6.708203933 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '6' to each side of the equation. -6 + 6 + x = 6.708203933 + 6 Combine like terms: -6 + 6 = 0 0 + x = 6.708203933 + 6 x = 6.708203933 + 6 Combine like terms: 6.708203933 + 6 = 12.708203933 x = 12.708203933 Simplifying x = 12.708203933

Subproblem 2

x + -6 = -6.708203933 Simplifying x + -6 = -6.708203933 Reorder the terms: -6 + x = -6.708203933 Solving -6 + x = -6.708203933 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '6' to each side of the equation. -6 + 6 + x = -6.708203933 + 6 Combine like terms: -6 + 6 = 0 0 + x = -6.708203933 + 6 x = -6.708203933 + 6 Combine like terms: -6.708203933 + 6 = -0.708203933 x = -0.708203933 Simplifying x = -0.708203933

Solution

The solution to the problem is based on the solutions from the subproblems. x = {12.708203933, -0.708203933}

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