x^2+18x=-18

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


Simplifying
x2 + 18x = -18

Reorder the terms:
18x + x2 = -18

Solving
18x + x2 = -18

Solving for variable 'x'.

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

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

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 = 63
81 + 18x + x2 = 63

Factor a perfect square on the left side:
(x + 9)(x + 9) = 63

Calculate the square root of the right side: 7.937253933

Break this problem into two subproblems by setting 
(x + 9) equal to 7.937253933 and -7.937253933.

Subproblem 1

x + 9 = 7.937253933 Simplifying x + 9 = 7.937253933 Reorder the terms: 9 + x = 7.937253933 Solving 9 + x = 7.937253933 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 = 7.937253933 + -9 Combine like terms: 9 + -9 = 0 0 + x = 7.937253933 + -9 x = 7.937253933 + -9 Combine like terms: 7.937253933 + -9 = -1.062746067 x = -1.062746067 Simplifying x = -1.062746067

Subproblem 2

x + 9 = -7.937253933 Simplifying x + 9 = -7.937253933 Reorder the terms: 9 + x = -7.937253933 Solving 9 + x = -7.937253933 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 = -7.937253933 + -9 Combine like terms: 9 + -9 = 0 0 + x = -7.937253933 + -9 x = -7.937253933 + -9 Combine like terms: -7.937253933 + -9 = -16.937253933 x = -16.937253933 Simplifying x = -16.937253933

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-1.062746067, -16.937253933}

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