Hi,

I hope someone can help. I'm suppose to prove thatx + ais a factor of(x + a)^5 + (x - c)^5 + (a - c)^5. The textbook solution is iff(x) = (x + a)^5 + (x - c)^5 + (a - c)^5, then f(-a) = 0. I don't totally understand this solution, so could someone please elaborate on this?

Best,

Olivia