x^2+20x=-9

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Solution for x^2+20x=-9 equation:


Simplifying
x2 + 20x = -9

Reorder the terms:
20x + x2 = -9

Solving
20x + x2 = -9

Solving for variable 'x'.

Reorder the terms:
9 + 20x + x2 = -9 + 9

Combine like terms: -9 + 9 = 0
9 + 20x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-9' to each side of the equation.
9 + 20x + -9 + x2 = 0 + -9

Reorder the terms:
9 + -9 + 20x + x2 = 0 + -9

Combine like terms: 9 + -9 = 0
0 + 20x + x2 = 0 + -9
20x + x2 = 0 + -9

Combine like terms: 0 + -9 = -9
20x + x2 = -9

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 = -9 + 100

Reorder the terms:
100 + 20x + x2 = -9 + 100

Combine like terms: -9 + 100 = 91
100 + 20x + x2 = 91

Factor a perfect square on the left side:
(x + 10)(x + 10) = 91

Calculate the square root of the right side: 9.539392014

Break this problem into two subproblems by setting 
(x + 10) equal to 9.539392014 and -9.539392014.

Subproblem 1

x + 10 = 9.539392014 Simplifying x + 10 = 9.539392014 Reorder the terms: 10 + x = 9.539392014 Solving 10 + x = 9.539392014 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 = 9.539392014 + -10 Combine like terms: 10 + -10 = 0 0 + x = 9.539392014 + -10 x = 9.539392014 + -10 Combine like terms: 9.539392014 + -10 = -0.460607986 x = -0.460607986 Simplifying x = -0.460607986

Subproblem 2

x + 10 = -9.539392014 Simplifying x + 10 = -9.539392014 Reorder the terms: 10 + x = -9.539392014 Solving 10 + x = -9.539392014 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 = -9.539392014 + -10 Combine like terms: 10 + -10 = 0 0 + x = -9.539392014 + -10 x = -9.539392014 + -10 Combine like terms: -9.539392014 + -10 = -19.539392014 x = -19.539392014 Simplifying x = -19.539392014

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-0.460607986, -19.539392014}

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