Math Is Fun Forum

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Please help me with this sets!

If A = {a, b, c}, B = {2, 4} and C = {x,y} write out the set S = (C x B) x A

THANK YOU!!

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help me with this sets!

hi mantastrike,

This looks like the 'cartesian product'.

eg

C X B = {(x,2), (x,4), (y,2), (y,4)}

Is that what you are after?

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Re: Please help me with this sets!

Yes EXACTLY, thank you very much.

But if possible can you please make it in detail?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help me with this sets!

hi mantastrike,

Well C X B = {(x,2), (x,4), (y,2), (y,4)} is half way there.

Then you want the cartesian product of that answer with A

{(x,2), (x,4), (y,2), (y,4)} x A = { ((x,2),a), ((x,2),b) ..............}  There'll be 12 elements altogether.

I suspect that you are expected to leave out the nested brackets and write the final answer as

{ (x,2,a), (x,2,b), ............. (y,4,c) }

The diagram below shows how to get them all.

Bob

Last edited by Bob (2011-04-25 01:14:43)

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob