2x^2+2x+21=0

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


Simplifying
2x2 + 2x + 21 = 0

Reorder the terms:
21 + 2x + 2x2 = 0

Solving
21 + 2x + 2x2 = 0

Solving for variable 'x'.

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

Divide each side by '2'.
10.5 + x + x2 = 0

Move the constant term to the right:

Add '-10.5' to each side of the equation.
10.5 + x + -10.5 + x2 = 0 + -10.5

Reorder the terms:
10.5 + -10.5 + x + x2 = 0 + -10.5

Combine like terms: 10.5 + -10.5 = 0.0
0.0 + x + x2 = 0 + -10.5
x + x2 = 0 + -10.5

Combine like terms: 0 + -10.5 = -10.5
x + x2 = -10.5

The x term is x.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
 + 0.25 + x2 = -10.5 + 0.25

Combine like terms:  + 0.25 = 1.25
1.25 + x2 = -10.5 + 0.25

Combine like terms: -10.5 + 0.25 = -10.25
1.25 + x2 = -10.25

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = -10.25

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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