x^2+21x+864=0

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Solution for x^2+21x+864=0 equation:


Simplifying
x2 + 21x + 864 = 0

Reorder the terms:
864 + 21x + x2 = 0

Solving
864 + 21x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-864' to each side of the equation.
864 + 21x + -864 + x2 = 0 + -864

Reorder the terms:
864 + -864 + 21x + x2 = 0 + -864

Combine like terms: 864 + -864 = 0
0 + 21x + x2 = 0 + -864
21x + x2 = 0 + -864

Combine like terms: 0 + -864 = -864
21x + x2 = -864

The x term is 21x.  Take half its coefficient (10.5).
Square it (110.25) and add it to both sides.

Add '110.25' to each side of the equation.
21x + 110.25 + x2 = -864 + 110.25

Reorder the terms:
110.25 + 21x + x2 = -864 + 110.25

Combine like terms: -864 + 110.25 = -753.75
110.25 + 21x + x2 = -753.75

Factor a perfect square on the left side:
(x + 10.5)(x + 10.5) = -753.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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