## SephI 3 years ago Did I do this correctly? "Create a set of numbers and call the set N. Describe a subset of N and explain why it is a subset of N."

1. SephI

N:{1, 2, 3 ,4 ,5 , 6 , 7 ... 20} C:{Numbers divisible by three} ~N{3, 6, 9, 12, 15, 18}

2. hartnn

yes, the subset is correct, but why the notation ~N ?

3. SephI

You an use: N' or ~N

4. hartnn

wouldn't N' or N~ be the complement of N ? use another name for subset, say M

5. SephI

I don't understand? "wouldn't N' or N~ be the complement of N ?" Isn't it a complement?

6. hartnn

but your question does not ask for complement, it asks for subset and complement and subsets are 2 different things

7. SephI

Can you explain the difference, please?

8. hartnn

yes, A = {1,2,3,4,5} let B be the even numbers in A so B= {2,4} here B is a subset of A since all elements of B are in A now complement of B = B' = B~ = {1,3,5} = elements not in B but are in A = odd elements of A got this much ?

9. hartnn

so for your example : N:{1, 2, 3 ,4 ,5 , 6 , 7 ... 20} Let C be subset of N defined by C:{Numbers divisible by three} C:{3, 6, 9, 12, 15, 18}

10. SephI

Okay, so ~B means elements in A that are not in B Subset is elements in B that are in A.

11. hartnn

so ~B means elements in A that are not in B , correct . subset is a set formed from A(universal set) such that elements of subset are all taken from A only

12. hartnn

so in your example, in subset c, you are just taking elements of N which are divisible by 3

13. SephI

Roger that.

14. hartnn

ask if any more doubts ?

15. SephI

I'm good. I'll be sure to message you in the future if I have any questions or concerns.

16. hartnn

good :) or feel free to tag me in your question

17. SephI

Ok.