x^2+5x+21=0

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Solution for x^2+5x+21=0 equation:


Simplifying
x2 + 5x + 21 = 0

Reorder the terms:
21 + 5x + x2 = 0

Solving
21 + 5x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-21' to each side of the equation.
21 + 5x + -21 + x2 = 0 + -21

Reorder the terms:
21 + -21 + 5x + x2 = 0 + -21

Combine like terms: 21 + -21 = 0
0 + 5x + x2 = 0 + -21
5x + x2 = 0 + -21

Combine like terms: 0 + -21 = -21
5x + x2 = -21

The x term is 5x.  Take half its coefficient (2.5).
Square it (6.25) and add it to both sides.

Add '6.25' to each side of the equation.
5x + 6.25 + x2 = -21 + 6.25

Reorder the terms:
6.25 + 5x + x2 = -21 + 6.25

Combine like terms: -21 + 6.25 = -14.75
6.25 + 5x + x2 = -14.75

Factor a perfect square on the left side:
(x + 2.5)(x + 2.5) = -14.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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