-x^2-2x+20=0

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Solution for -x^2-2x+20=0 equation:


Simplifying
-1x2 + -2x + 20 = 0

Reorder the terms:
20 + -2x + -1x2 = 0

Solving
20 + -2x + -1x2 = 0

Solving for variable 'x'.

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-20 + 2x + x2 = 0

Move the constant term to the right:

Add '20' to each side of the equation.
-20 + 2x + 20 + x2 = 0 + 20

Reorder the terms:
-20 + 20 + 2x + x2 = 0 + 20

Combine like terms: -20 + 20 = 0
0 + 2x + x2 = 0 + 20
2x + x2 = 0 + 20

Combine like terms: 0 + 20 = 20
2x + x2 = 20

The x term is 2x.  Take half its coefficient (1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
2x + 1 + x2 = 20 + 1

Reorder the terms:
1 + 2x + x2 = 20 + 1

Combine like terms: 20 + 1 = 21
1 + 2x + x2 = 21

Factor a perfect square on the left side:
(x + 1)(x + 1) = 21

Calculate the square root of the right side: 4.582575695

Break this problem into two subproblems by setting 
(x + 1) equal to 4.582575695 and -4.582575695.

Subproblem 1

x + 1 = 4.582575695 Simplifying x + 1 = 4.582575695 Reorder the terms: 1 + x = 4.582575695 Solving 1 + x = 4.582575695 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1' to each side of the equation. 1 + -1 + x = 4.582575695 + -1 Combine like terms: 1 + -1 = 0 0 + x = 4.582575695 + -1 x = 4.582575695 + -1 Combine like terms: 4.582575695 + -1 = 3.582575695 x = 3.582575695 Simplifying x = 3.582575695

Subproblem 2

x + 1 = -4.582575695 Simplifying x + 1 = -4.582575695 Reorder the terms: 1 + x = -4.582575695 Solving 1 + x = -4.582575695 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1' to each side of the equation. 1 + -1 + x = -4.582575695 + -1 Combine like terms: 1 + -1 = 0 0 + x = -4.582575695 + -1 x = -4.582575695 + -1 Combine like terms: -4.582575695 + -1 = -5.582575695 x = -5.582575695 Simplifying x = -5.582575695

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.582575695, -5.582575695}

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