x^2+13x-9=12

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Solution for x^2+13x-9=12 equation:


Simplifying
x2 + 13x + -9 = 12

Reorder the terms:
-9 + 13x + x2 = 12

Solving
-9 + 13x + x2 = 12

Solving for variable 'x'.

Reorder the terms:
-9 + -12 + 13x + x2 = 12 + -12

Combine like terms: -9 + -12 = -21
-21 + 13x + x2 = 12 + -12

Combine like terms: 12 + -12 = 0
-21 + 13x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '21' to each side of the equation.
-21 + 13x + 21 + x2 = 0 + 21

Reorder the terms:
-21 + 21 + 13x + x2 = 0 + 21

Combine like terms: -21 + 21 = 0
0 + 13x + x2 = 0 + 21
13x + x2 = 0 + 21

Combine like terms: 0 + 21 = 21
13x + x2 = 21

The x term is 13x.  Take half its coefficient (6.5).
Square it (42.25) and add it to both sides.

Add '42.25' to each side of the equation.
13x + 42.25 + x2 = 21 + 42.25

Reorder the terms:
42.25 + 13x + x2 = 21 + 42.25

Combine like terms: 21 + 42.25 = 63.25
42.25 + 13x + x2 = 63.25

Factor a perfect square on the left side:
(x + 6.5)(x + 6.5) = 63.25

Calculate the square root of the right side: 7.95298686

Break this problem into two subproblems by setting 
(x + 6.5) equal to 7.95298686 and -7.95298686.

Subproblem 1

x + 6.5 = 7.95298686 Simplifying x + 6.5 = 7.95298686 Reorder the terms: 6.5 + x = 7.95298686 Solving 6.5 + x = 7.95298686 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-6.5' to each side of the equation. 6.5 + -6.5 + x = 7.95298686 + -6.5 Combine like terms: 6.5 + -6.5 = 0.0 0.0 + x = 7.95298686 + -6.5 x = 7.95298686 + -6.5 Combine like terms: 7.95298686 + -6.5 = 1.45298686 x = 1.45298686 Simplifying x = 1.45298686

Subproblem 2

x + 6.5 = -7.95298686 Simplifying x + 6.5 = -7.95298686 Reorder the terms: 6.5 + x = -7.95298686 Solving 6.5 + x = -7.95298686 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-6.5' to each side of the equation. 6.5 + -6.5 + x = -7.95298686 + -6.5 Combine like terms: 6.5 + -6.5 = 0.0 0.0 + x = -7.95298686 + -6.5 x = -7.95298686 + -6.5 Combine like terms: -7.95298686 + -6.5 = -14.45298686 x = -14.45298686 Simplifying x = -14.45298686

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.45298686, -14.45298686}

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