2y^2+y+21=0

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

Simplifying
2y2 + y + 21 = 0

Reorder the terms:
21 + y + 2y2 = 0

Solving
21 + y + 2y2 = 0

Solving for variable 'y'.

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

Divide each side by '2'.
10.5 + 0.5y + y2 = 0

Move the constant term to the right:

Add '-10.5' to each side of the equation.
10.5 + 0.5y + -10.5 + y2 = 0 + -10.5

Reorder the terms:
10.5 + -10.5 + 0.5y + y2 = 0 + -10.5

Combine like terms: 10.5 + -10.5 = 0.0
0.0 + 0.5y + y2 = 0 + -10.5
0.5y + y2 = 0 + -10.5

Combine like terms: 0 + -10.5 = -10.5
0.5y + y2 = -10.5

The y term is y.  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.
0.5y + 0.25 + y2 = -10.5 + 0.25

Reorder the terms:
0.25 + 0.5y + y2 = -10.5 + 0.25

Combine like terms: -10.5 + 0.25 = -10.25
0.25 + 0.5y + y2 = -10.25

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

Can't calculate square root of the right side.

The solution to this equation could not be determined.