x^2+12x=39

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Solution for x^2+12x=39 equation:


Simplifying
x2 + 12x = 39

Reorder the terms:
12x + x2 = 39

Solving
12x + x2 = 39

Solving for variable 'x'.

Reorder the terms:
-39 + 12x + x2 = 39 + -39

Combine like terms: 39 + -39 = 0
-39 + 12x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '39' to each side of the equation.
-39 + 12x + 39 + x2 = 0 + 39

Reorder the terms:
-39 + 39 + 12x + x2 = 0 + 39

Combine like terms: -39 + 39 = 0
0 + 12x + x2 = 0 + 39
12x + x2 = 0 + 39

Combine like terms: 0 + 39 = 39
12x + x2 = 39

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 = 39 + 36

Reorder the terms:
36 + 12x + x2 = 39 + 36

Combine like terms: 39 + 36 = 75
36 + 12x + x2 = 75

Factor a perfect square on the left side:
(x + 6)(x + 6) = 75

Calculate the square root of the right side: 8.660254038

Break this problem into two subproblems by setting 
(x + 6) equal to 8.660254038 and -8.660254038.

Subproblem 1

x + 6 = 8.660254038 Simplifying x + 6 = 8.660254038 Reorder the terms: 6 + x = 8.660254038 Solving 6 + x = 8.660254038 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 = 8.660254038 + -6 Combine like terms: 6 + -6 = 0 0 + x = 8.660254038 + -6 x = 8.660254038 + -6 Combine like terms: 8.660254038 + -6 = 2.660254038 x = 2.660254038 Simplifying x = 2.660254038

Subproblem 2

x + 6 = -8.660254038 Simplifying x + 6 = -8.660254038 Reorder the terms: 6 + x = -8.660254038 Solving 6 + x = -8.660254038 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 = -8.660254038 + -6 Combine like terms: 6 + -6 = 0 0 + x = -8.660254038 + -6 x = -8.660254038 + -6 Combine like terms: -8.660254038 + -6 = -14.660254038 x = -14.660254038 Simplifying x = -14.660254038

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.660254038, -14.660254038}

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