20x-x^2=80

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


Simplifying
20x + -1x2 = 80

Solving
20x + -1x2 = 80

Solving for variable 'x'.

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

Combine like terms: 80 + -80 = 0
-80 + 20x + -1x2 = 0

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 = 20
100 + -20x + x2 = 20

Factor a perfect square on the left side:
(x + -10)(x + -10) = 20

Calculate the square root of the right side: 4.472135955

Break this problem into two subproblems by setting 
(x + -10) equal to 4.472135955 and -4.472135955.

Subproblem 1

x + -10 = 4.472135955 Simplifying x + -10 = 4.472135955 Reorder the terms: -10 + x = 4.472135955 Solving -10 + x = 4.472135955 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 = 4.472135955 + 10 Combine like terms: -10 + 10 = 0 0 + x = 4.472135955 + 10 x = 4.472135955 + 10 Combine like terms: 4.472135955 + 10 = 14.472135955 x = 14.472135955 Simplifying x = 14.472135955

Subproblem 2

x + -10 = -4.472135955 Simplifying x + -10 = -4.472135955 Reorder the terms: -10 + x = -4.472135955 Solving -10 + x = -4.472135955 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 = -4.472135955 + 10 Combine like terms: -10 + 10 = 0 0 + x = -4.472135955 + 10 x = -4.472135955 + 10 Combine like terms: -4.472135955 + 10 = 5.527864045 x = 5.527864045 Simplifying x = 5.527864045

Solution

The solution to the problem is based on the solutions from the subproblems. x = {14.472135955, 5.527864045}

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