9x^2+31x-108=0

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Solution for 9x^2+31x-108=0 equation:


Simplifying
9x2 + 31x + -108 = 0

Reorder the terms:
-108 + 31x + 9x2 = 0

Solving
-108 + 31x + 9x2 = 0

Solving for variable 'x'.

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

Divide each side by '9'.
-12 + 3.444444444x + x2 = 0

Move the constant term to the right:

Add '12' to each side of the equation.
-12 + 3.444444444x + 12 + x2 = 0 + 12

Reorder the terms:
-12 + 12 + 3.444444444x + x2 = 0 + 12

Combine like terms: -12 + 12 = 0
0 + 3.444444444x + x2 = 0 + 12
3.444444444x + x2 = 0 + 12

Combine like terms: 0 + 12 = 12
3.444444444x + x2 = 12

The x term is 3.444444444x.  Take half its coefficient (1.722222222).
Square it (2.966049382) and add it to both sides.

Add '2.966049382' to each side of the equation.
3.444444444x + 2.966049382 + x2 = 12 + 2.966049382

Reorder the terms:
2.966049382 + 3.444444444x + x2 = 12 + 2.966049382

Combine like terms: 12 + 2.966049382 = 14.966049382
2.966049382 + 3.444444444x + x2 = 14.966049382

Factor a perfect square on the left side:
(x + 1.722222222)(x + 1.722222222) = 14.966049382

Calculate the square root of the right side: 3.868597857

Break this problem into two subproblems by setting 
(x + 1.722222222) equal to 3.868597857 and -3.868597857.

Subproblem 1

x + 1.722222222 = 3.868597857 Simplifying x + 1.722222222 = 3.868597857 Reorder the terms: 1.722222222 + x = 3.868597857 Solving 1.722222222 + x = 3.868597857 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.722222222' to each side of the equation. 1.722222222 + -1.722222222 + x = 3.868597857 + -1.722222222 Combine like terms: 1.722222222 + -1.722222222 = 0.000000000 0.000000000 + x = 3.868597857 + -1.722222222 x = 3.868597857 + -1.722222222 Combine like terms: 3.868597857 + -1.722222222 = 2.146375635 x = 2.146375635 Simplifying x = 2.146375635

Subproblem 2

x + 1.722222222 = -3.868597857 Simplifying x + 1.722222222 = -3.868597857 Reorder the terms: 1.722222222 + x = -3.868597857 Solving 1.722222222 + x = -3.868597857 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.722222222' to each side of the equation. 1.722222222 + -1.722222222 + x = -3.868597857 + -1.722222222 Combine like terms: 1.722222222 + -1.722222222 = 0.000000000 0.000000000 + x = -3.868597857 + -1.722222222 x = -3.868597857 + -1.722222222 Combine like terms: -3.868597857 + -1.722222222 = -5.590820079 x = -5.590820079 Simplifying x = -5.590820079

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.146375635, -5.590820079}

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