x^2+20x=-18

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Solution for x^2+20x=-18 equation:


Simplifying
x2 + 20x = -18

Reorder the terms:
20x + x2 = -18

Solving
20x + x2 = -18

Solving for variable 'x'.

Reorder the terms:
18 + 20x + x2 = -18 + 18

Combine like terms: -18 + 18 = 0
18 + 20x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-18' to each side of the equation.
18 + 20x + -18 + x2 = 0 + -18

Reorder the terms:
18 + -18 + 20x + x2 = 0 + -18

Combine like terms: 18 + -18 = 0
0 + 20x + x2 = 0 + -18
20x + x2 = 0 + -18

Combine like terms: 0 + -18 = -18
20x + x2 = -18

The x term is 20x.  Take half its coefficient (10).
Square it (100) and add it to both sides.

Add '100' to each side of the equation.
20x + 100 + x2 = -18 + 100

Reorder the terms:
100 + 20x + x2 = -18 + 100

Combine like terms: -18 + 100 = 82
100 + 20x + x2 = 82

Factor a perfect square on the left side:
(x + 10)(x + 10) = 82

Calculate the square root of the right side: 9.055385138

Break this problem into two subproblems by setting 
(x + 10) equal to 9.055385138 and -9.055385138.

Subproblem 1

x + 10 = 9.055385138 Simplifying x + 10 = 9.055385138 Reorder the terms: 10 + x = 9.055385138 Solving 10 + x = 9.055385138 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10' to each side of the equation. 10 + -10 + x = 9.055385138 + -10 Combine like terms: 10 + -10 = 0 0 + x = 9.055385138 + -10 x = 9.055385138 + -10 Combine like terms: 9.055385138 + -10 = -0.944614862 x = -0.944614862 Simplifying x = -0.944614862

Subproblem 2

x + 10 = -9.055385138 Simplifying x + 10 = -9.055385138 Reorder the terms: 10 + x = -9.055385138 Solving 10 + x = -9.055385138 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10' to each side of the equation. 10 + -10 + x = -9.055385138 + -10 Combine like terms: 10 + -10 = 0 0 + x = -9.055385138 + -10 x = -9.055385138 + -10 Combine like terms: -9.055385138 + -10 = -19.055385138 x = -19.055385138 Simplifying x = -19.055385138

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-0.944614862, -19.055385138}

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