3x^2-12x-40=0

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Solution for 3x^2-12x-40=0 equation:


Simplifying
3x2 + -12x + -40 = 0

Reorder the terms:
-40 + -12x + 3x2 = 0

Solving
-40 + -12x + 3x2 = 0

Solving for variable 'x'.

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

Divide each side by '3'.
-13.33333333 + -4x + x2 = 0

Move the constant term to the right:

Add '13.33333333' to each side of the equation.
-13.33333333 + -4x + 13.33333333 + x2 = 0 + 13.33333333

Reorder the terms:
-13.33333333 + 13.33333333 + -4x + x2 = 0 + 13.33333333

Combine like terms: -13.33333333 + 13.33333333 = 0.00000000
0.00000000 + -4x + x2 = 0 + 13.33333333
-4x + x2 = 0 + 13.33333333

Combine like terms: 0 + 13.33333333 = 13.33333333
-4x + x2 = 13.33333333

The x term is -4x.  Take half its coefficient (-2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
-4x + 4 + x2 = 13.33333333 + 4

Reorder the terms:
4 + -4x + x2 = 13.33333333 + 4

Combine like terms: 13.33333333 + 4 = 17.33333333
4 + -4x + x2 = 17.33333333

Factor a perfect square on the left side:
(x + -2)(x + -2) = 17.33333333

Calculate the square root of the right side: 4.163331999

Break this problem into two subproblems by setting 
(x + -2) equal to 4.163331999 and -4.163331999.

Subproblem 1

x + -2 = 4.163331999 Simplifying x + -2 = 4.163331999 Reorder the terms: -2 + x = 4.163331999 Solving -2 + x = 4.163331999 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = 4.163331999 + 2 Combine like terms: -2 + 2 = 0 0 + x = 4.163331999 + 2 x = 4.163331999 + 2 Combine like terms: 4.163331999 + 2 = 6.163331999 x = 6.163331999 Simplifying x = 6.163331999

Subproblem 2

x + -2 = -4.163331999 Simplifying x + -2 = -4.163331999 Reorder the terms: -2 + x = -4.163331999 Solving -2 + x = -4.163331999 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = -4.163331999 + 2 Combine like terms: -2 + 2 = 0 0 + x = -4.163331999 + 2 x = -4.163331999 + 2 Combine like terms: -4.163331999 + 2 = -2.163331999 x = -2.163331999 Simplifying x = -2.163331999

Solution

The solution to the problem is based on the solutions from the subproblems. x = {6.163331999, -2.163331999}

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