-x^2+39x+20=0

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Solution for -x^2+39x+20=0 equation:


Simplifying
-1x2 + 39x + 20 = 0

Reorder the terms:
20 + 39x + -1x2 = 0

Solving
20 + 39x + -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 + -39x + x2 = 0

Move the constant term to the right:

Add '20' to each side of the equation.
-20 + -39x + 20 + x2 = 0 + 20

Reorder the terms:
-20 + 20 + -39x + x2 = 0 + 20

Combine like terms: -20 + 20 = 0
0 + -39x + x2 = 0 + 20
-39x + x2 = 0 + 20

Combine like terms: 0 + 20 = 20
-39x + x2 = 20

The x term is -39x.  Take half its coefficient (-19.5).
Square it (380.25) and add it to both sides.

Add '380.25' to each side of the equation.
-39x + 380.25 + x2 = 20 + 380.25

Reorder the terms:
380.25 + -39x + x2 = 20 + 380.25

Combine like terms: 20 + 380.25 = 400.25
380.25 + -39x + x2 = 400.25

Factor a perfect square on the left side:
(x + -19.5)(x + -19.5) = 400.25

Calculate the square root of the right side: 20.006249024

Break this problem into two subproblems by setting 
(x + -19.5) equal to 20.006249024 and -20.006249024.

Subproblem 1

x + -19.5 = 20.006249024 Simplifying x + -19.5 = 20.006249024 Reorder the terms: -19.5 + x = 20.006249024 Solving -19.5 + x = 20.006249024 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '19.5' to each side of the equation. -19.5 + 19.5 + x = 20.006249024 + 19.5 Combine like terms: -19.5 + 19.5 = 0.0 0.0 + x = 20.006249024 + 19.5 x = 20.006249024 + 19.5 Combine like terms: 20.006249024 + 19.5 = 39.506249024 x = 39.506249024 Simplifying x = 39.506249024

Subproblem 2

x + -19.5 = -20.006249024 Simplifying x + -19.5 = -20.006249024 Reorder the terms: -19.5 + x = -20.006249024 Solving -19.5 + x = -20.006249024 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '19.5' to each side of the equation. -19.5 + 19.5 + x = -20.006249024 + 19.5 Combine like terms: -19.5 + 19.5 = 0.0 0.0 + x = -20.006249024 + 19.5 x = -20.006249024 + 19.5 Combine like terms: -20.006249024 + 19.5 = -0.506249024 x = -0.506249024 Simplifying x = -0.506249024

Solution

The solution to the problem is based on the solutions from the subproblems. x = {39.506249024, -0.506249024}

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