x^2+12x=9

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Solution for x^2+12x=9 equation:


Simplifying
x2 + 12x = 9

Reorder the terms:
12x + x2 = 9

Solving
12x + x2 = 9

Solving for variable 'x'.

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

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

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 = 0.708203933 x = 0.708203933 Simplifying x = 0.708203933

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 = -12.708203933 x = -12.708203933 Simplifying x = -12.708203933

Solution

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

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