-x^2-12x=-87

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Solution for -x^2-12x=-87 equation:


Simplifying
-1x2 + -12x = -87

Reorder the terms:
-12x + -1x2 = -87

Solving
-12x + -1x2 = -87

Solving for variable 'x'.

Reorder the terms:
87 + -12x + -1x2 = -87 + 87

Combine like terms: -87 + 87 = 0
87 + -12x + -1x2 = 0

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

Divide each side by '-1'.
-87 + 12x + x2 = 0

Move the constant term to the right:

Add '87' to each side of the equation.
-87 + 12x + 87 + x2 = 0 + 87

Reorder the terms:
-87 + 87 + 12x + x2 = 0 + 87

Combine like terms: -87 + 87 = 0
0 + 12x + x2 = 0 + 87
12x + x2 = 0 + 87

Combine like terms: 0 + 87 = 87
12x + x2 = 87

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 = 87 + 36

Reorder the terms:
36 + 12x + x2 = 87 + 36

Combine like terms: 87 + 36 = 123
36 + 12x + x2 = 123

Factor a perfect square on the left side:
(x + 6)(x + 6) = 123

Calculate the square root of the right side: 11.090536506

Break this problem into two subproblems by setting 
(x + 6) equal to 11.090536506 and -11.090536506.

Subproblem 1

x + 6 = 11.090536506 Simplifying x + 6 = 11.090536506 Reorder the terms: 6 + x = 11.090536506 Solving 6 + x = 11.090536506 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 = 11.090536506 + -6 Combine like terms: 6 + -6 = 0 0 + x = 11.090536506 + -6 x = 11.090536506 + -6 Combine like terms: 11.090536506 + -6 = 5.090536506 x = 5.090536506 Simplifying x = 5.090536506

Subproblem 2

x + 6 = -11.090536506 Simplifying x + 6 = -11.090536506 Reorder the terms: 6 + x = -11.090536506 Solving 6 + x = -11.090536506 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 = -11.090536506 + -6 Combine like terms: 6 + -6 = 0 0 + x = -11.090536506 + -6 x = -11.090536506 + -6 Combine like terms: -11.090536506 + -6 = -17.090536506 x = -17.090536506 Simplifying x = -17.090536506

Solution

The solution to the problem is based on the solutions from the subproblems. x = {5.090536506, -17.090536506}

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