Homework 3

We have discussed the following concepts, examples, and solutions in class. Write these in your own words. For examples, feel free to give the same as or different from the ones given in class.

Explain when to use addition and when to use multiplication in combinatorics. Give examples for both.
Give one example of a problem that requires both addition and multiplication to count the number of ways to do something.
Write solutions to problems 1, 3, and 5 in this problem set on combinatorics. Be sure to explain your reasoning in detail. A quick calculation and an answer are not sufficient.