5x^2+15x+28=0

Solution for 5x^2+15x+28=0 equation:

Simplifying
5x2 + 15x + 28 = 0

Reorder the terms:
28 + 15x + 5x2 = 0

Solving
28 + 15x + 5x2 = 0

Solving for variable 'x'.

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

Divide each side by '5'.
5.6 + 3x + x2 = 0

Move the constant term to the right:

Add '-5.6' to each side of the equation.
5.6 + 3x + -5.6 + x2 = 0 + -5.6

Reorder the terms:
5.6 + -5.6 + 3x + x2 = 0 + -5.6

Combine like terms: 5.6 + -5.6 = 0.0
0.0 + 3x + x2 = 0 + -5.6
3x + x2 = 0 + -5.6

Combine like terms: 0 + -5.6 = -5.6
3x + x2 = -5.6

The x term is 3x.  Take half its coefficient (1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
3x + 2.25 + x2 = -5.6 + 2.25

Reorder the terms:
2.25 + 3x + x2 = -5.6 + 2.25

Combine like terms: -5.6 + 2.25 = -3.35
2.25 + 3x + x2 = -3.35

Factor a perfect square on the left side:
(x + 1.5)(x + 1.5) = -3.35

Can't calculate square root of the right side.

The solution to this equation could not be determined.