x^2-3x-39=0

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Solution for x^2-3x-39=0 equation:


Simplifying
x2 + -3x + -39 = 0

Reorder the terms:
-39 + -3x + x2 = 0

Solving
-39 + -3x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '39' to each side of the equation.
-39 + -3x + 39 + x2 = 0 + 39

Reorder the terms:
-39 + 39 + -3x + x2 = 0 + 39

Combine like terms: -39 + 39 = 0
0 + -3x + x2 = 0 + 39
-3x + x2 = 0 + 39

Combine like terms: 0 + 39 = 39
-3x + x2 = 39

The x term is -3x.  Take half its coefficient (-1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
-3x + 2.25 + x2 = 39 + 2.25

Reorder the terms:
2.25 + -3x + x2 = 39 + 2.25

Combine like terms: 39 + 2.25 = 41.25
2.25 + -3x + x2 = 41.25

Factor a perfect square on the left side:
(x + -1.5)(x + -1.5) = 41.25

Calculate the square root of the right side: 6.422616289

Break this problem into two subproblems by setting 
(x + -1.5) equal to 6.422616289 and -6.422616289.

Subproblem 1

x + -1.5 = 6.422616289 Simplifying x + -1.5 = 6.422616289 Reorder the terms: -1.5 + x = 6.422616289 Solving -1.5 + x = 6.422616289 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.5' to each side of the equation. -1.5 + 1.5 + x = 6.422616289 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = 6.422616289 + 1.5 x = 6.422616289 + 1.5 Combine like terms: 6.422616289 + 1.5 = 7.922616289 x = 7.922616289 Simplifying x = 7.922616289

Subproblem 2

x + -1.5 = -6.422616289 Simplifying x + -1.5 = -6.422616289 Reorder the terms: -1.5 + x = -6.422616289 Solving -1.5 + x = -6.422616289 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.5' to each side of the equation. -1.5 + 1.5 + x = -6.422616289 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = -6.422616289 + 1.5 x = -6.422616289 + 1.5 Combine like terms: -6.422616289 + 1.5 = -4.922616289 x = -4.922616289 Simplifying x = -4.922616289

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.922616289, -4.922616289}

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