In this chapter you have seen that a binomial expansion can help you find the probability of an outcome of a series of events when each event has only two possible results (such as success or failure). When there are three possible results instead of two, you can use trinomials in a similar way. Expand each trinomial given below. The first answer will have 6 terms, the second will have 10 terms, and the third will have 15 terms.
(x + y + z)2 (x + y + z)3 (x + y + z)4
Write a formula for the expansion of (x + y + z)n.