x^2+12x=-15

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Solution for x^2+12x=-15 equation:


Simplifying
x2 + 12x = -15

Reorder the terms:
12x + x2 = -15

Solving
12x + x2 = -15

Solving for variable 'x'.

Reorder the terms:
15 + 12x + x2 = -15 + 15

Combine like terms: -15 + 15 = 0
15 + 12x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-15' to each side of the equation.
15 + 12x + -15 + x2 = 0 + -15

Reorder the terms:
15 + -15 + 12x + x2 = 0 + -15

Combine like terms: 15 + -15 = 0
0 + 12x + x2 = 0 + -15
12x + x2 = 0 + -15

Combine like terms: 0 + -15 = -15
12x + x2 = -15

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 = -15 + 36

Reorder the terms:
36 + 12x + x2 = -15 + 36

Combine like terms: -15 + 36 = 21
36 + 12x + x2 = 21

Factor a perfect square on the left side:
(x + 6)(x + 6) = 21

Calculate the square root of the right side: 4.582575695

Break this problem into two subproblems by setting 
(x + 6) equal to 4.582575695 and -4.582575695.

Subproblem 1

x + 6 = 4.582575695 Simplifying x + 6 = 4.582575695 Reorder the terms: 6 + x = 4.582575695 Solving 6 + x = 4.582575695 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 = 4.582575695 + -6 Combine like terms: 6 + -6 = 0 0 + x = 4.582575695 + -6 x = 4.582575695 + -6 Combine like terms: 4.582575695 + -6 = -1.417424305 x = -1.417424305 Simplifying x = -1.417424305

Subproblem 2

x + 6 = -4.582575695 Simplifying x + 6 = -4.582575695 Reorder the terms: 6 + x = -4.582575695 Solving 6 + x = -4.582575695 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 = -4.582575695 + -6 Combine like terms: 6 + -6 = 0 0 + x = -4.582575695 + -6 x = -4.582575695 + -6 Combine like terms: -4.582575695 + -6 = -10.582575695 x = -10.582575695 Simplifying x = -10.582575695

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-1.417424305, -10.582575695}

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