x^2-7x-39=0

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Solution for x^2-7x-39=0 equation:


Simplifying
x2 + -7x + -39 = 0

Reorder the terms:
-39 + -7x + x2 = 0

Solving
-39 + -7x + 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 + -7x + 39 + x2 = 0 + 39

Reorder the terms:
-39 + 39 + -7x + x2 = 0 + 39

Combine like terms: -39 + 39 = 0
0 + -7x + x2 = 0 + 39
-7x + x2 = 0 + 39

Combine like terms: 0 + 39 = 39
-7x + x2 = 39

The x term is -7x.  Take half its coefficient (-3.5).
Square it (12.25) and add it to both sides.

Add '12.25' to each side of the equation.
-7x + 12.25 + x2 = 39 + 12.25

Reorder the terms:
12.25 + -7x + x2 = 39 + 12.25

Combine like terms: 39 + 12.25 = 51.25
12.25 + -7x + x2 = 51.25

Factor a perfect square on the left side:
(x + -3.5)(x + -3.5) = 51.25

Calculate the square root of the right side: 7.158910532

Break this problem into two subproblems by setting 
(x + -3.5) equal to 7.158910532 and -7.158910532.

Subproblem 1

x + -3.5 = 7.158910532 Simplifying x + -3.5 = 7.158910532 Reorder the terms: -3.5 + x = 7.158910532 Solving -3.5 + x = 7.158910532 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.5' to each side of the equation. -3.5 + 3.5 + x = 7.158910532 + 3.5 Combine like terms: -3.5 + 3.5 = 0.0 0.0 + x = 7.158910532 + 3.5 x = 7.158910532 + 3.5 Combine like terms: 7.158910532 + 3.5 = 10.658910532 x = 10.658910532 Simplifying x = 10.658910532

Subproblem 2

x + -3.5 = -7.158910532 Simplifying x + -3.5 = -7.158910532 Reorder the terms: -3.5 + x = -7.158910532 Solving -3.5 + x = -7.158910532 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.5' to each side of the equation. -3.5 + 3.5 + x = -7.158910532 + 3.5 Combine like terms: -3.5 + 3.5 = 0.0 0.0 + x = -7.158910532 + 3.5 x = -7.158910532 + 3.5 Combine like terms: -7.158910532 + 3.5 = -3.658910532 x = -3.658910532 Simplifying x = -3.658910532

Solution

The solution to the problem is based on the solutions from the subproblems. x = {10.658910532, -3.658910532}

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