Algebra Know-It-ALL

Part One 167

Question 9-4

In this book, here’s how we symbolize various sets of numbers.

• The set of natural numbers is N.


• The set of integers is Z.


• The set of rational numbers is Q.


• The set of irrational numbers is S.


• The set of real numbers is R.

Which of these sets are proper subsets of which? Which pairs of sets are disjoint?

Answer 9-4

Here’s how the sets are related:

• N⊂Z, N⊂Q, and N⊂R


• Z⊂Q and Z⊂R


• Q⊂R


• S⊂R


• N∩S=∅,Z∩S=∅, and Q∩S=∅

0

1

2

Positive

number

line

This point

corresponds to π

3

Start

Finish

1 unit

Circle rolls upward along line without slipping

Figure 10-4 Illustration for

Answer 9-3.