Set builder notation

And

Here's a good one:

http://www.justanswer.com/questions/1cvxp-1write-following-roster-form-set

Hey ..

Check this out:

http://fd.valenciacc.edu/file/dgil2/COT2104_Practice%203.pdf

Pretty close, eh?

Here's some answers worth checking:

http://www.justanswer.com/questions/1i88m-1-2-pts-write-following-roster

http://fd.valenciacc.edu/file/dgil2/COT2104_Practice%203.pdf
that is good for practice, but it doesn't show the answers.  It doesn't help much if I don't know how to solve it.  LoL

Your right ..

Boy, I was on a roll though.  All of a sudden I though I was back in school.  What would it be like, going to school with google?

No wonder they call it Yahoo!

Another way to describe a set is to use set builder notation. We characterize all those
elements in the set by stating the property or properties they must have to be members. For
instance, the set O of all odd positive integers less than 10 can be written as

O = {x | x is an odd positive integer less than 10},

or, specifying the universe as the set of positive integers, as

O = {x  Z+ | x is odd and x < 10}.

We often use this type of notation to describe sets when it is impossible to list all the elements
of the set. For instance, the set Q+ of all positive rational numbers can be written as
Q+ = {x  R | x = p/q, for some positive integers p and q.

These sets, each denoted using a boldface letter, play an important role in discrete
mathematics:
N = {0, 1, 2, 3, . . .}, the set of natural numbers
Z = {. . . ,2,1, 0, 1, 2, . . .}, the set of integers
Z+ = {1, 2, 3, . . .}, the set of positive integers
Q = {p/q | p  Z, q  Z, and q = 0}, the set of rational numbers
R, the set of real numbers

(Note that some people do not consider 0 a natural number, so be careful to check how the term
natural numbers is used when you read other books.)

Sets can have other sets as members, as this Example  illustrates.

EXAMPLE  The set {N,Z,Q,R} is a set containing four elements, each of which is a set. The four elements
of this set are N, the set of natural numbers; Z, the set of integers; Q, the set of rational numbers;
and R, the set of real numbers.

Remark:
Note that the concept of a datatype, or type, in computer science is built upon the
concept of a set. In particular, a datatype or type is the name of a set, together with a set of
operations that can be performed on objects from that set. For example, boolean is the name of
the set {0, 1} together with operators on one or more elements of this set, such as AND, OR,
and NOT.

So ..

For the first one:

{0, 3, 6, 9, 12}

Answer: { 3k | k   * {0} }

And ..

the second one (which is actually):

{-3, -2, -1, 0, 1, 2, 3}

A = { x / x ¬ I, -4 < x < 4}

I is integer and it is read as

A is a set of x such that x belongs to integer and x is greater than -4 and less than4

Finally ..

The last one:

{m, n, o, p}

Answer is:

x | x is an element of {m , n , o , p }

For the second one I had A={x | -3 <=x<=3

Is that the same thing as what you put?  i don't understand the not integer part that you have.