I can show that -1 isn't a multiple root, but I don't think that's really answering the question. Can anyone elaborate?
I used Theorem 20.5. Let f = the polynomial in the question and take the derivative. Prove there is no common factor between f and f prime. I'm not sure if this is correct though.
right. that's what i was using, but can you tell me how you showed that they don't have common factors?