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Fletchnuts

Help Help Help!!!!!! 4. Use set notation to identify the shaded region. (Note: The universe is not shaded) ******Attachment Below********

  • one year ago
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  1. Fletchnuts
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    • one year ago
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  2. AccessDenied
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    So, what sets are being shaded here? (For a moment, I'm only looking at which ones have ANY shading. We'll deal with parts in a second.)

    • one year ago
  3. Fletchnuts
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    Well A and part of C are shaded.

    • one year ago
  4. AccessDenied
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    Alright. So, we're going to have A combined with some part of C. It appears here that the only part of C that is missing from the shading is the part where it intersects with B. So, if we remove B from C by subtraction, C - B, then we now are representing only the part of C not in B. We then just add in all of A to this set: We originally removed a bit of the shaded part, but here we actually add it back in. A u (C - B) Would that make sense?

    • one year ago
  5. AccessDenied
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    * I think some classes use a slanted mark "A \ B" for subtraction rather than a minus sign "A - B", so you may use whichever you are familiar with.

    • one year ago
  6. Fletchnuts
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    sorta my understanding of set notation is not all there. lol it really confusing My teacher hasnt showed us anything with the / mark or -. we have just been using U and and upside down U and also '

    • one year ago
  7. AccessDenied
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    Hmm... not sure how to define that region without a subtraction. One thing to note about sets is that they don't accumulate unless you add unique elements to them. If you add in the same elements as that are in the set, they would just disappear since we already have that element. U is like set addition. A U B takes the elements of A together with the elements of B. When they share elements, those elements don't repeat in the union. n / the hill thing is like finding what two sets have in common. A n B gives you the elements in both A and B. I imagine it like putting A and B on top of each other where they have the same elements and then chopping off the parts that are falling off. :P The set subtraction '-' or '\' is like taking all the parts of one set out of another. A - B means, 'take A and remove everything it shares with B. I hope maybe that helps. Unless I'm just repeating stuff you knew. :P

    • one year ago
  8. AccessDenied
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    * The complement thing A' is sort of like U \ A, taking your universal set and then excluding A. Literally, 'everything not A'

    • one year ago
  9. Fletchnuts
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    ok that helps some. lol i just feel really dumb when it comes to this kind of stuff.

    • one year ago
  10. AccessDenied
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    Hmm, did you only begin stuff with sets recently? I think people tend to struggle with it at first since it's like a whole new system of rules with weird 'set' things rather than numbers. :P

    • one year ago
  11. Fletchnuts
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    Yes I'm in a freshman college pre-algebra course. This is the last problem I have on a math project due tomorrow.

    • one year ago
  12. AccessDenied
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    Ah, okay. Cool. :) Well, I am not able to think of another way of writing it other than A u (C - B) or something crazier involving subtractions. I think that is the best way of writing it.

    • one year ago
  13. Fletchnuts
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    that might be correct let me check over my note really quick and ill get back to you. thanks

    • one year ago
  14. AccessDenied
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    You're welcome. :)

    • one year ago
  15. Fletchnuts
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    See if this helps. I'm just retarded and can't learn anything from this but this looks just like what were learning. http://www.math.hawaii.edu/~williamdemeo/Math371-Summer2011/SetOperationsAndVenDiagrams.pdf

    • one year ago
  16. Fletchnuts
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    scroll to the bottom of that page.

    • one year ago
  17. AccessDenied
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    Hmm... It looks like \(A \cup B^c\) contains the shaded region including the stuff outside our set, so we could intersect it with \( A \cup C \) to remove the excess outside the set: \((A \cup B^c) \ \cap (A \cup C)\)

    • one year ago
  18. AccessDenied
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    The \(A \cup B^c\) is shown on the second-to-last slide.

    • one year ago
  19. Fletchnuts
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    yeah i see that and that makes sense. so is that the answer?

    • one year ago
  20. Fletchnuts
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    this is not math! lol i hate this kind of stuff

    • one year ago
  21. AccessDenied
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    You could probably pull the A out by reverse distribution of the union over intersections. \( M \cup (N \cap P) = (M \cup N) \cap (M \cup P)\) \( A \cup (B^c \cap C) = (A \cup B^c) \cap (A \cup C) \) That'd look a little better I think. In fact, it kind of looks like A u (C - B) like originally. I guess A u (C n B') is the same thing as that subtraction. :P

    • one year ago
  22. Fletchnuts
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    yeah i guess it must be the same thing, who knows though. i guess ill find out when i turn it in tomorrow. lol

    • one year ago
  23. AccessDenied
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    I'm thinking about it... |dw:1352244687932:dw| Yeah, it seems to work. :D Set notation is so fun sometimes. lol

    • one year ago
  24. Fletchnuts
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    so is it A ∪ (C ∩ B')?

    • one year ago
  25. AccessDenied
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    Yep. :)

    • one year ago
  26. Fletchnuts
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    thanks so much!!!!!!! you have been so much help!!!!!!!!!!!!!

    • one year ago
  27. AccessDenied
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    You're welcome! I learned some things myself as well. I never knew about that complement trick instead of subtraction of sets. ;)

    • one year ago
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