x^2+18x-18=0

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


Simplifying
x2 + 18x + -18 = 0

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

Solving
-18 + 18x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '18' to each side of the equation.
-18 + 18x + 18 + x2 = 0 + 18

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

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

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

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 = 18 + 81

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

Combine like terms: 18 + 81 = 99
81 + 18x + x2 = 99

Factor a perfect square on the left side:
(x + 9)(x + 9) = 99

Calculate the square root of the right side: 9.949874371

Break this problem into two subproblems by setting 
(x + 9) equal to 9.949874371 and -9.949874371.

Subproblem 1

x + 9 = 9.949874371 Simplifying x + 9 = 9.949874371 Reorder the terms: 9 + x = 9.949874371 Solving 9 + x = 9.949874371 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 = 9.949874371 + -9 Combine like terms: 9 + -9 = 0 0 + x = 9.949874371 + -9 x = 9.949874371 + -9 Combine like terms: 9.949874371 + -9 = 0.949874371 x = 0.949874371 Simplifying x = 0.949874371

Subproblem 2

x + 9 = -9.949874371 Simplifying x + 9 = -9.949874371 Reorder the terms: 9 + x = -9.949874371 Solving 9 + x = -9.949874371 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 = -9.949874371 + -9 Combine like terms: 9 + -9 = 0 0 + x = -9.949874371 + -9 x = -9.949874371 + -9 Combine like terms: -9.949874371 + -9 = -18.949874371 x = -18.949874371 Simplifying x = -18.949874371

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.949874371, -18.949874371}

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