x^2+18x=-7

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Solution for x^2+18x=-7 equation:


Simplifying
x2 + 18x = -7

Reorder the terms:
18x + x2 = -7

Solving
18x + x2 = -7

Solving for variable 'x'.

Reorder the terms:
7 + 18x + x2 = -7 + 7

Combine like terms: -7 + 7 = 0
7 + 18x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-7' to each side of the equation.
7 + 18x + -7 + x2 = 0 + -7

Reorder the terms:
7 + -7 + 18x + x2 = 0 + -7

Combine like terms: 7 + -7 = 0
0 + 18x + x2 = 0 + -7
18x + x2 = 0 + -7

Combine like terms: 0 + -7 = -7
18x + x2 = -7

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 = -7 + 81

Reorder the terms:
81 + 18x + x2 = -7 + 81

Combine like terms: -7 + 81 = 74
81 + 18x + x2 = 74

Factor a perfect square on the left side:
(x + 9)(x + 9) = 74

Calculate the square root of the right side: 8.602325267

Break this problem into two subproblems by setting 
(x + 9) equal to 8.602325267 and -8.602325267.

Subproblem 1

x + 9 = 8.602325267 Simplifying x + 9 = 8.602325267 Reorder the terms: 9 + x = 8.602325267 Solving 9 + x = 8.602325267 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 = 8.602325267 + -9 Combine like terms: 9 + -9 = 0 0 + x = 8.602325267 + -9 x = 8.602325267 + -9 Combine like terms: 8.602325267 + -9 = -0.397674733 x = -0.397674733 Simplifying x = -0.397674733

Subproblem 2

x + 9 = -8.602325267 Simplifying x + 9 = -8.602325267 Reorder the terms: 9 + x = -8.602325267 Solving 9 + x = -8.602325267 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 = -8.602325267 + -9 Combine like terms: 9 + -9 = 0 0 + x = -8.602325267 + -9 x = -8.602325267 + -9 Combine like terms: -8.602325267 + -9 = -17.602325267 x = -17.602325267 Simplifying x = -17.602325267

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-0.397674733, -17.602325267}

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