5y^2+14y+21=0

Solution for 5y^2+14y+21=0 equation:

Simplifying
5y2 + 14y + 21 = 0

Reorder the terms:
21 + 14y + 5y2 = 0

Solving
21 + 14y + 5y2 = 0

Solving for variable 'y'.

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

Divide each side by '5'.
4.2 + 2.8y + y2 = 0

Move the constant term to the right:

Add '-4.2' to each side of the equation.
4.2 + 2.8y + -4.2 + y2 = 0 + -4.2

Reorder the terms:
4.2 + -4.2 + 2.8y + y2 = 0 + -4.2

Combine like terms: 4.2 + -4.2 = 0.0
0.0 + 2.8y + y2 = 0 + -4.2
2.8y + y2 = 0 + -4.2

Combine like terms: 0 + -4.2 = -4.2
2.8y + y2 = -4.2

The y term is 2.8y.  Take half its coefficient (1.4).
Square it (1.96) and add it to both sides.

Add '1.96' to each side of the equation.
2.8y + 1.96 + y2 = -4.2 + 1.96

Reorder the terms:
1.96 + 2.8y + y2 = -4.2 + 1.96

Combine like terms: -4.2 + 1.96 = -2.24
1.96 + 2.8y + y2 = -2.24

Factor a perfect square on the left side:
(y + 1.4)(y + 1.4) = -2.24

Can't calculate square root of the right side.

The solution to this equation could not be determined.