200 likes | 323 Views
PowerPoint Presentation . Section 2.6 Infinite Sets. The idea of Infinity . Infinity is not a number. Infinity is an idea related to numbers. It is believed that there are an infinite number of stars in the universe -- the number of stars cannot be counted. Infinite Sets.
E N D
PowerPoint Presentation Section 2.6 Infinite Sets
The idea of Infinity • Infinity is not a number. • Infinity is an idea related to numbers. • It is believed that there are an infinite number of stars in the universe -- the number of stars cannot be counted.
Infinite Sets • An infinite set contains an uncountable number of elements. • One way to show that a set is infinite is by using the definition of infinite sets: An infinite set can be placed in a one-to-one correspondence with a proper subset of itself
The Set of Natural Numbers is an Infinite Set … • The Natural Numbers is the set: { 1,2,3,4,…} • A Proper Subset of the Natural Numbers is the set: { 2,3,4,5…} • These sets can be put in a one-to-one correspondence.
The Multiples of 10 are an infinite set • We can use any proper subset of the infinite set for the one-to-one correspondence. We pick one with a pattern so we can name the general term: • 10, 20, 30, 40… • 20,40,60,80… • 100, 200, 300…
Countable Sets and Aleph-Null • An infinite set is countable if it can be put in a one-to-one correspondence with the Natural Numbers. • Countable sets have a cardinal number of “aleph-null”. The symbol for aleph-null is:
Arithmetic of Aleph-Null + = - 10 =
Arithmetic of Aleph-Null 3 + = ? 5 - 4 = ?
Arithmetic of Aleph-Null 3 + = 5 - 4 = 0