Examples:

(1) A = {tiger, lion, puma, cheetah, leopard, cougar, ocelot} (this is a set of large species of cats)
(2) A = {a, b, c, ..., z} (this is a set consisting of the lowercase letters of the alphabet)
(3) A = {-1, -2, -3, ...} (this is a set of the negative numbers)

Answers

2014-06-03T17:01:08+08:00
Basically, set is a collection. Sets are not necessarily made from numbers - few fruits on a plate can be a set: {apple, banana, durian} - things/numbers in braces are set.

{1,2,3,4,5} - finite set
{1,2,3,4,5,6,...} - infinite set

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2014-06-03T17:20:16+08:00
Examples:

(1) A = {tiger, lion, puma, cheetah, leopard, cougar, ocelot} (this is a set of large species of cats) 
(2) A = {a, b, c, ..., z} (this is a set consisting of the lowercase letters of the alphabet) 
(3) A = {-1, -2, -3, ...} (this is a set of the negative numbers)
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