-x^2-20x+80=0

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Solution for -x^2-20x+80=0 equation:


Simplifying
-1x2 + -20x + 80 = 0

Reorder the terms:
80 + -20x + -1x2 = 0

Solving
80 + -20x + -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'.
-80 + 20x + x2 = 0

Move the constant term to the right:

Add '80' to each side of the equation.
-80 + 20x + 80 + x2 = 0 + 80

Reorder the terms:
-80 + 80 + 20x + x2 = 0 + 80

Combine like terms: -80 + 80 = 0
0 + 20x + x2 = 0 + 80
20x + x2 = 0 + 80

Combine like terms: 0 + 80 = 80
20x + x2 = 80

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 = 80 + 100

Reorder the terms:
100 + 20x + x2 = 80 + 100

Combine like terms: 80 + 100 = 180
100 + 20x + x2 = 180

Factor a perfect square on the left side:
(x + 10)(x + 10) = 180

Calculate the square root of the right side: 13.416407865

Break this problem into two subproblems by setting 
(x + 10) equal to 13.416407865 and -13.416407865.

Subproblem 1

x + 10 = 13.416407865 Simplifying x + 10 = 13.416407865 Reorder the terms: 10 + x = 13.416407865 Solving 10 + x = 13.416407865 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 = 13.416407865 + -10 Combine like terms: 10 + -10 = 0 0 + x = 13.416407865 + -10 x = 13.416407865 + -10 Combine like terms: 13.416407865 + -10 = 3.416407865 x = 3.416407865 Simplifying x = 3.416407865

Subproblem 2

x + 10 = -13.416407865 Simplifying x + 10 = -13.416407865 Reorder the terms: 10 + x = -13.416407865 Solving 10 + x = -13.416407865 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 = -13.416407865 + -10 Combine like terms: 10 + -10 = 0 0 + x = -13.416407865 + -10 x = -13.416407865 + -10 Combine like terms: -13.416407865 + -10 = -23.416407865 x = -23.416407865 Simplifying x = -23.416407865

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.416407865, -23.416407865}

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