z^2+2z+15=0

Solution for z^2+2z+15=0 equation:

Simplifying
z2 + 2z + 15 = 0

Reorder the terms:
15 + 2z + z2 = 0

Solving
15 + 2z + z2 = 0

Solving for variable 'z'.

Begin completing the square.

Move the constant term to the right:

Add '-15' to each side of the equation.
15 + 2z + -15 + z2 = 0 + -15

Reorder the terms:
15 + -15 + 2z + z2 = 0 + -15

Combine like terms: 15 + -15 = 0
0 + 2z + z2 = 0 + -15
2z + z2 = 0 + -15

Combine like terms: 0 + -15 = -15
2z + z2 = -15

The z term is 2z.  Take half its coefficient (1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
2z + 1 + z2 = -15 + 1

Reorder the terms:
1 + 2z + z2 = -15 + 1

Combine like terms: -15 + 1 = -14
1 + 2z + z2 = -14

Factor a perfect square on the left side:
(z + 1)(z + 1) = -14

Can't calculate square root of the right side.

The solution to this equation could not be determined.