My gut response to this was, "Man, why does ANYBODY promote rage?" But your question was not a question for my opinion, but to help you in writing your response.
Many students in your class will respond to the personal history of Mr. Carmichael with the society that he was experiencing. That would be a good answer to your question, but I suggest that you move this answer in a different direction.
Take a look at what was happening in a broader sense that would actually "allow" this group to be violent. It wasn't just that he was an angry black man throwing out hatred. Something in society actually ALLOWED him to kick at them. Consider that the society, as a whole. They had their sons in Viet Nam (dying)... they had hippies who were high disrupting everything that was normal... and people were just beginning to save the whales, the trees, and the earth. This meant that they were NOT looking at "black rights." All of the "causes" were jostling for attention. Now.... YOU put that together in your response to the question about Mr. Carmichael. Why do you think he promoted violence?