-x^2+9x=84

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Solution for -x^2+9x=84 equation:


Simplifying
-1x2 + 9x = 84

Reorder the terms:
9x + -1x2 = 84

Solving
9x + -1x2 = 84

Solving for variable 'x'.

Reorder the terms:
-84 + 9x + -1x2 = 84 + -84

Combine like terms: 84 + -84 = 0
-84 + 9x + -1x2 = 0

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

Divide each side by '-1'.
84 + -9x + x2 = 0

Move the constant term to the right:

Add '-84' to each side of the equation.
84 + -9x + -84 + x2 = 0 + -84

Reorder the terms:
84 + -84 + -9x + x2 = 0 + -84

Combine like terms: 84 + -84 = 0
0 + -9x + x2 = 0 + -84
-9x + x2 = 0 + -84

Combine like terms: 0 + -84 = -84
-9x + x2 = -84

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 = -84 + 20.25

Reorder the terms:
20.25 + -9x + x2 = -84 + 20.25

Combine like terms: -84 + 20.25 = -63.75
20.25 + -9x + x2 = -63.75

Factor a perfect square on the left side:
(x + -4.5)(x + -4.5) = -63.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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