-x^2+9x+321=0

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Solution for -x^2+9x+321=0 equation:


Simplifying
-1x2 + 9x + 321 = 0

Reorder the terms:
321 + 9x + -1x2 = 0

Solving
321 + 9x + -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'.
-321 + -9x + x2 = 0

Move the constant term to the right:

Add '321' to each side of the equation.
-321 + -9x + 321 + x2 = 0 + 321

Reorder the terms:
-321 + 321 + -9x + x2 = 0 + 321

Combine like terms: -321 + 321 = 0
0 + -9x + x2 = 0 + 321
-9x + x2 = 0 + 321

Combine like terms: 0 + 321 = 321
-9x + x2 = 321

The x term is -9x.  Take half its coefficient (-4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
-9x + 20.25 + x2 = 321 + 20.25

Reorder the terms:
20.25 + -9x + x2 = 321 + 20.25

Combine like terms: 321 + 20.25 = 341.25
20.25 + -9x + x2 = 341.25

Factor a perfect square on the left side:
(x + -4.5)(x + -4.5) = 341.25

Calculate the square root of the right side: 18.472953202

Break this problem into two subproblems by setting 
(x + -4.5) equal to 18.472953202 and -18.472953202.

Subproblem 1

x + -4.5 = 18.472953202 Simplifying x + -4.5 = 18.472953202 Reorder the terms: -4.5 + x = 18.472953202 Solving -4.5 + x = 18.472953202 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + x = 18.472953202 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = 18.472953202 + 4.5 x = 18.472953202 + 4.5 Combine like terms: 18.472953202 + 4.5 = 22.972953202 x = 22.972953202 Simplifying x = 22.972953202

Subproblem 2

x + -4.5 = -18.472953202 Simplifying x + -4.5 = -18.472953202 Reorder the terms: -4.5 + x = -18.472953202 Solving -4.5 + x = -18.472953202 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + x = -18.472953202 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + x = -18.472953202 + 4.5 x = -18.472953202 + 4.5 Combine like terms: -18.472953202 + 4.5 = -13.972953202 x = -13.972953202 Simplifying x = -13.972953202

Solution

The solution to the problem is based on the solutions from the subproblems. x = {22.972953202, -13.972953202}

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