## anonymous 4 years ago Simplify the following unions and intersections of intervals.

1. anonymous

$\eta \cup \mathbb{R}$

2. anonymous

The N stands for a set of all natural numbers.

3. anonymous

The R stands for a set of all real numbers.

4. anonymous

what does $\eta$ stand for?

5. anonymous

oh maybe $\mathbb N \cap \mathbb R$

6. anonymous

Yes it shows it like that except the U is facing up? And how did you post them like that i was looking for them.

7. anonymous

$\mathbb N \cap \mathbb R=\mathbb N$ since the natural numbers live inside the real numbers and $\mathbb N \cup \mathbb R=\mathbb R$ for the same reason

8. anonymous

\mathbb N

9. anonymous

Oh thanks and sorry i am sorta new to this site so don't know exactly how to post stuff correctly.

10. anonymous

I have 2 more problems like this one sec.

11. anonymous

that is ok, easier just to describe the symbol pallet is only good for some things. i was showing off in latex

12. anonymous

Oh what is latex? And how do i post and upside down unison like you did?

13. anonymous

Hey satellite how do you post an upside down unison?

14. anonymous

\cup

15. anonymous

\cap

16. anonymous

if you want to see any code, right click and it will show up. you can also copy and paste

17. anonymous

$A^c\cap B^c=(A\cup B)^c$

18. anonymous

Oh do i just click show format or what?$\left[ 2,\infty)\cap(-4,7)\cap(-3,2 \right]$

19. anonymous

this is my next problem ^

20. anonymous

so you are looking for what is in common to all three intervals. easy if you drew them

21. anonymous

I think so yes...

22. anonymous

|dw:1327692676456:dw|

23. anonymous

the only number that $[2,\infty)$ and $(-3,2]$ have in common is 2

24. anonymous

so that is the only number in the intersection

25. anonymous

It says simplify the unions and intersections of intervals.

26. anonymous

27. anonymous

Oh well that was simple so it is just what they have in common?

28. anonymous

yeah intersection mean in both

29. anonymous

$(-4.8,-3.5)\cap \mathbb{Z}^+$

30. anonymous

this is last problem of these kind... don't mind + above Z it should just be Z

31. anonymous

do you know what $\mathbb Z^+$ is? (nice looking isn't it?)

32. anonymous

ah that is different. $\mathbb Z$ is all integers $\{...,-3,-2,1,0,1,2,3,...\}$

33. anonymous

In my book it stands for set of all integers.

34. anonymous

so you are looking for all integers in the interval you have. how many are there?

35. anonymous

i think only one in there is -4

36. anonymous

Only one integer correct.

37. anonymous

then that is the only one in the intersection