x^2-4x-39=0

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Solution for x^2-4x-39=0 equation:


Simplifying
x2 + -4x + -39 = 0

Reorder the terms:
-39 + -4x + x2 = 0

Solving
-39 + -4x + 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 + -4x + 39 + x2 = 0 + 39

Reorder the terms:
-39 + 39 + -4x + x2 = 0 + 39

Combine like terms: -39 + 39 = 0
0 + -4x + x2 = 0 + 39
-4x + x2 = 0 + 39

Combine like terms: 0 + 39 = 39
-4x + x2 = 39

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 = 39 + 4

Reorder the terms:
4 + -4x + x2 = 39 + 4

Combine like terms: 39 + 4 = 43
4 + -4x + x2 = 43

Factor a perfect square on the left side:
(x + -2)(x + -2) = 43

Calculate the square root of the right side: 6.557438524

Break this problem into two subproblems by setting 
(x + -2) equal to 6.557438524 and -6.557438524.

Subproblem 1

x + -2 = 6.557438524 Simplifying x + -2 = 6.557438524 Reorder the terms: -2 + x = 6.557438524 Solving -2 + x = 6.557438524 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 = 6.557438524 + 2 Combine like terms: -2 + 2 = 0 0 + x = 6.557438524 + 2 x = 6.557438524 + 2 Combine like terms: 6.557438524 + 2 = 8.557438524 x = 8.557438524 Simplifying x = 8.557438524

Subproblem 2

x + -2 = -6.557438524 Simplifying x + -2 = -6.557438524 Reorder the terms: -2 + x = -6.557438524 Solving -2 + x = -6.557438524 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 = -6.557438524 + 2 Combine like terms: -2 + 2 = 0 0 + x = -6.557438524 + 2 x = -6.557438524 + 2 Combine like terms: -6.557438524 + 2 = -4.557438524 x = -4.557438524 Simplifying x = -4.557438524

Solution

The solution to the problem is based on the solutions from the subproblems. x = {8.557438524, -4.557438524}

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