Introduction to integers
Sets
A set is a collection of objects with similar properties.
Example:
1.
The set of the letters from English alphabet:
{a, b, c, d, e, f, g, h, i,j, k, I, m, n, o, p, q, r, s, t, u, v, w, x, y, z]
2.
The set of even integers between 2 and 8
{4,6}
a,b,c,d,e, f,g,h,/,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,4,6, ..., are elements
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The elements are objects from the set
Roster method encloses the list of all elements
Example:
1.
The set of the first five natural numbers
{1,2,3,4,5}
2.
The set of NATURALNUMBERSi
N* = {1,2,3,4,5,6,,.}
3.
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The set of WHOLE NUMBERS:
N = {0,1,2,3,4,5,6,...}
4.
WA
The set of INTEGER NUMBERS:
-outers #r 2£#*tob
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1 = f-y..., -5, -4, -3, -2, -1,0,1, 2, 3,4,5, ...fco
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Exercise 1: a) Use the roster method to find the set of natural numbers less than 5.
b) Use the roster method to write the set of negative integers greater than -9.