x^2+18x-39=0

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Solution for x^2+18x-39=0 equation:


Simplifying
x2 + 18x + -39 = 0

Reorder the terms:
-39 + 18x + x2 = 0

Solving
-39 + 18x + 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 + 18x + 39 + x2 = 0 + 39

Reorder the terms:
-39 + 39 + 18x + x2 = 0 + 39

Combine like terms: -39 + 39 = 0
0 + 18x + x2 = 0 + 39
18x + x2 = 0 + 39

Combine like terms: 0 + 39 = 39
18x + x2 = 39

The x term is 18x.  Take half its coefficient (9).
Square it (81) and add it to both sides.

Add '81' to each side of the equation.
18x + 81 + x2 = 39 + 81

Reorder the terms:
81 + 18x + x2 = 39 + 81

Combine like terms: 39 + 81 = 120
81 + 18x + x2 = 120

Factor a perfect square on the left side:
(x + 9)(x + 9) = 120

Calculate the square root of the right side: 10.95445115

Break this problem into two subproblems by setting 
(x + 9) equal to 10.95445115 and -10.95445115.

Subproblem 1

x + 9 = 10.95445115 Simplifying x + 9 = 10.95445115 Reorder the terms: 9 + x = 10.95445115 Solving 9 + x = 10.95445115 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + x = 10.95445115 + -9 Combine like terms: 9 + -9 = 0 0 + x = 10.95445115 + -9 x = 10.95445115 + -9 Combine like terms: 10.95445115 + -9 = 1.95445115 x = 1.95445115 Simplifying x = 1.95445115

Subproblem 2

x + 9 = -10.95445115 Simplifying x + 9 = -10.95445115 Reorder the terms: 9 + x = -10.95445115 Solving 9 + x = -10.95445115 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + x = -10.95445115 + -9 Combine like terms: 9 + -9 = 0 0 + x = -10.95445115 + -9 x = -10.95445115 + -9 Combine like terms: -10.95445115 + -9 = -19.95445115 x = -19.95445115 Simplifying x = -19.95445115

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.95445115, -19.95445115}

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