1.What is a set?

2.What does the following set mean: \(A = {1, 15, 35}\)

3.Explain why the following notation doesn't make sense: \(d \in {a, b, c}\)

4.Consider the sets \(A = {1, 15, 35}\) and \(B = {1, 15}\). Is it fair to say that \(B \in A\)? Why or why not?

5.Describe the following set: \({x : x+ 3 \in \mathbb{N}}\)

6.Define the following special sets:
- a. \(\emptyset\)
- b. \(\mathcal{U}\)
- c. \(\mathbb{N}\)
- d. \(\mathbb{Z}\)
- e. \(\mathbb{Q}\)
- f. \(\mathbb{R}\)
- g. \(\mathcal{P}(A)\)

7.What's the cardinality of the following set: \(A={3,4,…,20}\)

9.Consider the set \(A = {a, b, c}\). What's the power set of \(A\), \(\mathcal{P}(A)\)?

10.What is the union of two sets?

11.What is the intersection of two sets?

12.Consider the sets \(A={1,2}\) and \(B={3,4,5}\). What is the Cartesian product, \(A \times B\)?