Results 1 to 7 of 7

Math Help - sets

  1. #1
    Newbie
    Joined
    Mar 2008
    Posts
    7

    sets

    for any natural number n let Bn = {x|x ε N and x ≤ n}. Describe each of the following sets in the form {x | property}

    a) Bm - Bn, where m > n
    b) Bm U Bn, where m ≤ n
    c) Bm ∩ Bn, where m ≤ n
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Mar 2008
    Posts
    7
    having trouble getting started, terminology is screwing me up a bit
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78
    Quote Originally Posted by bretf26 View Post
    for any natural number n let Bn = {x|x ε N and x ≤ n}. Describe each of the following sets in the form {x | property}

    a) Bm - Bn, where m > n
    b) Bm U Bn, where m ≤ n
    c) Bm ∩ Bn, where m ≤ n
    Maybe this will help you visualize it.

    B_m={1,2,3...n,(n+1),(n+2),... m} and
    B_n={1,2,3...n} when n < m

    so B_m-B_n  =  {(n+1),...m}

    {x| n < x \le m}
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78
    I didn't mention the fact that x is an integer. (that is important)

    sorry
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Mar 2008
    Posts
    7
    for Bm U Bn, where m ≤ n

    I think I understand it more, but the (n+1) confuses me a bit. Is this attempt correct at all?

    Bn = {1, 2, 3...n}
    Bm = {1, 2, 3...n, (n-1), (n-2)...m}

    so Bm U Bn = {1....n}

    {x | m ≤ x ≤ n}
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78
    Quote Originally Posted by bretf26 View Post
    for Bm U Bn, where m ≤ n

    I think I understand it more, but the (n+1) confuses me a bit. Is this attempt correct at all?

    Bn = {1, 2, 3...n}
    Bm = {1, 2, 3...n, (n-1), (n-2)...m}

    so Bm U Bn = {1....n}

    {x | m ≤ x ≤ n}

    not quite..

    B_n={1,2,3...m,(m+1),(m+2),...n}

    because m \le n

    B_m={1,2,3,...m}

    This time we were asked to find the union of two sets. The union is all of the stuff in B_n and all of the stuff in B_m

    B_n U B_m={x|1 \le x \le n and x \epsilon {N}}
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Mar 2008
    Posts
    7
    thanks for the help, I understand it now!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Open sets and sets of interior points
    Posted in the Differential Geometry Forum
    Replies: 1
    Last Post: August 9th 2011, 04:10 AM
  2. Metric spaces, open sets, and closed sets
    Posted in the Differential Geometry Forum
    Replies: 4
    Last Post: March 16th 2011, 06:17 PM
  3. Replies: 9
    Last Post: November 6th 2010, 01:47 PM
  4. Approximation of borel sets from the top with closed sets.
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: February 18th 2010, 09:51 AM
  5. how to show these sets are 95% confidence sets
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: February 11th 2009, 10:08 PM

Search Tags


/mathhelpforum @mathhelpforum