d^2+8d+15=0

Solution for d^2+8d+15=0 equation:

Simplifying
d2 + 8d + 15 = 0

Reorder the terms:
15 + 8d + d2 = 0

Solving
15 + 8d + d2 = 0

Solving for variable 'd'.

Factor a trinomial.
(5 + d)(3 + d) = 0

Subproblem 1
Set the factor '(5 + d)' equal to zero and attempt to solve:

Simplifying
5 + d = 0

Solving
5 + d = 0

Move all terms containing d to the left, all other terms to the right.

Add '-5' to each side of the equation.
5 + -5 + d = 0 + -5

Combine like terms: 5 + -5 = 0
0 + d = 0 + -5
d = 0 + -5

Combine like terms: 0 + -5 = -5
d = -5

Simplifying
d = -5
Subproblem 2
Set the factor '(3 + d)' equal to zero and attempt to solve:

Simplifying
3 + d = 0

Solving
3 + d = 0

Move all terms containing d to the left, all other terms to the right.

Add '-3' to each side of the equation.
3 + -3 + d = 0 + -3

Combine like terms: 3 + -3 = 0
0 + d = 0 + -3
d = 0 + -3

Combine like terms: 0 + -3 = -3
d = -3

Simplifying
d = -3
Solution
d = {-5, -3}