x^2+18x=-2

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


Simplifying
x2 + 18x = -2

Reorder the terms:
18x + x2 = -2

Solving
18x + x2 = -2

Solving for variable 'x'.

Reorder the terms:
2 + 18x + x2 = -2 + 2

Combine like terms: -2 + 2 = 0
2 + 18x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-2' to each side of the equation.
2 + 18x + -2 + x2 = 0 + -2

Reorder the terms:
2 + -2 + 18x + x2 = 0 + -2

Combine like terms: 2 + -2 = 0
0 + 18x + x2 = 0 + -2
18x + x2 = 0 + -2

Combine like terms: 0 + -2 = -2
18x + x2 = -2

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 = -2 + 81

Reorder the terms:
81 + 18x + x2 = -2 + 81

Combine like terms: -2 + 81 = 79
81 + 18x + x2 = 79

Factor a perfect square on the left side:
(x + 9)(x + 9) = 79

Calculate the square root of the right side: 8.888194417

Break this problem into two subproblems by setting 
(x + 9) equal to 8.888194417 and -8.888194417.

Subproblem 1

x + 9 = 8.888194417 Simplifying x + 9 = 8.888194417 Reorder the terms: 9 + x = 8.888194417 Solving 9 + x = 8.888194417 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 = 8.888194417 + -9 Combine like terms: 9 + -9 = 0 0 + x = 8.888194417 + -9 x = 8.888194417 + -9 Combine like terms: 8.888194417 + -9 = -0.111805583 x = -0.111805583 Simplifying x = -0.111805583

Subproblem 2

x + 9 = -8.888194417 Simplifying x + 9 = -8.888194417 Reorder the terms: 9 + x = -8.888194417 Solving 9 + x = -8.888194417 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 = -8.888194417 + -9 Combine like terms: 9 + -9 = 0 0 + x = -8.888194417 + -9 x = -8.888194417 + -9 Combine like terms: -8.888194417 + -9 = -17.888194417 x = -17.888194417 Simplifying x = -17.888194417

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-0.111805583, -17.888194417}

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