1. Does the set of real numbers, R, form a group under subtraction? Justify.
2. Consider the integers modulo 12, Z12, under multiplication.
a) Determine whether [5] and [6] have multiplicative inverses in Z12.
Hint: It’s not necessary to construct a multiplication table as it’s quite big.
You can just form all the possible products of each numbers with the others.
b) Does Z12 form a group under multiplication? Justify.
3. Write 47.35123123123… as a ratio of two integers.
EPP (3rd Edition):
Section 4.1 #12, 28, 52
Section 4.2 #23
Section 6.1 #29, 35d
Section 6.2 #31
http://fit.ac.ir/en/download/ebooksclub.org__Discrete_Mathematics_with_Applications.pdf
