set of positive integers is a finite set or infinite set
Answers
Example:
A = {0, 2, 4, 6, 8, …, 100}
C = {x : x is an integer, 1 < x < 10}
An infinite set is a set which is not finite. It is not possible to explicitly list out all the elements of an infinite set.
Example:
T = {x : x is a triangle}
N is the set of natural numbers
A is the set of fractions
The number of elements in a finite set A is denoted by n(A).
Example:
If A is the set of positive integers less than 12 then
A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11} and n(A) = 11
If C is the set of numbers which are also multiples of 3 then
C = {3, 6, 9, …} and C is an infinite set
If D is the set of integers x defined by –3 < x < 6 then
D = {–2, –1, 0, 1, 2, 3, 4, 5} and n(D) = 8
If Q is the set of letters in the word ‘HELLO’ then
Q = {H, E, L, O } , n(Q) = 4 ← ‘L’ is not repeated.
Infinite vs. Finite Number Sets
The word finite means
• having bounds
• a set that contains a countable number of elements.
• the set starts and stops
The word infinite means
• the set in which the number of elements cannot be counted or determined (never ending)
• the set can continue forever in the beginning, or the end, or both
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