Descartes rule of signs tells you that there is a maximum of 4 real positive roots and 1 real negative root.
Graphing the equation suggests that there are 3 real roots!
All my learning says this is NOT possible since complex conjugate roots must occur in pairs.
I do not understand this and will have to study it further.
If you get a better answer either here or in class, I would appreciate your letting me know.
Thanks!
4/30/2019
I am sorry this took so long and it may be no longer of any help to you.
The equation has 4 real roots (not 3) and 2 were so close together I could not see them on my graphing calculator. Therefore: 4 real roots and one pair of complex conjugates!