## jollysailorbold 2 years ago Could somebody explain what this sign means? (I'll draw it below.)

1. jollysailorbold

|dw:1359007073471:dw| (It has to do with inequalities, sets, and subsets)

2. jollysailorbold

for example: \[A \subseteq B\]

3. skullpatrol

The set A is a subset of the set B or the same as the set B.

4. Andresfon12

discrete math indeed

5. jollysailorbold

hmm, and if it's just like this? \[A \subset B\] ?

6. skullpatrol

Then the set A is a subset of the set B.

7. jollysailorbold

Ah, I see. And \[A \cup B \] ?

8. Andresfon12

union

9. skullpatrol

\$\$a \le b\$\$ compared to \$\$a< b\$\$

10. Andresfon12

def: the union of the sets a and b, denote by A U B is the st that contain those elements that are either in a or in b , or both

11. jollysailorbold

Ah wait I'm still a bit confused. So if I'm asked: If A = {2, 4, 6, 8, 10} and B = {4, 8, 10}, then which of the following statements is false? 1) A ∩ B = B 2) B⊆B 3) A⊂B Then it would be 3 because A is not a subset of B, it is B that is a subset of A.. right?

12. Andresfon12

u need to prove the three staments

13. jollysailorbold

No, I don't. I need to choose which one out of these (A ∩ B = B, B⊆B, and A⊂B) are false.

14. Andresfon12

(1) {2, 4, 6, 8, 10} ∩ {4, 8, 10}

15. Andresfon12

that a intersection

16. jollysailorbold

I'm lost :/

17. Andresfon12

∩=intersection ∪= union

18. Andresfon12

(1) {2, 4, 6, 8, 10} ∩ {4, 8, 10}= {4, 8, 10} true because is a intersection {2, 4, 6, 8, 10} ∪ {4, 8, 10}= {4, 8, 10} false is support to be equal to {2, 4, 6, 8, 10}

19. jollysailorbold

It's not A ∩ B = B because it's an intersection, nor B⊆B because {4, 8, 10} is the same as {4, 8, 10}.. so the one that's false is what I said earlier: A⊂B...

20. Andresfon12

yes that false

21. Andresfon12

the second one is also true

22. Andresfon12

s⊆s or empty set ⊆ empty set

23. jollysailorbold

Thank you for you help (even though, honestly, it was very confusing...)

24. Andresfon12

if u read the book u will understand it better

25. jollysailorbold

I didn't have a book. I have online schooling where they rarely give me well written lessons. (If I could just read the book I wouldn't be using OpenStudy.)

26. Andresfon12

i don't know if this book good for you.i will give you name if wants to read it. Discretematics and its appliacation seven or six edition by kenneth H. Rosen

27. Andresfon12

have a great day

28. jollysailorbold

Oh okay thank you! And you too!