1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Discrete math

  1. Nov 11, 2005 #1

    How do I proove :

    (A U B) x (A U B) = (A x A) U (B x B)

    if and only if : (A C B) or (B C A) ?

    Please Advice,
    Dimitry Haritonov
  2. jcsd
  3. Nov 11, 2005 #2

    Tom Mattson

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Please show what you've done so far, as per the Guidelines you agreed to.
  4. Nov 12, 2005 #3
    Dear Tom,

    First of all I need to proove the two sides.

    so I've started with first side when ACB:

    (a,b)E(AUB)x(AUB) => aE(AUB) and bE(AUB) => if ACB so AUB=B => aEB and bEB => (a,b)E(BxB)

    the second side:

    (a,b)E(AxA)U(BxB) => here I have a little problem, I don't sure that I can to state that: if ACB so (AxA)U(BxB) = (BXB).

    If It's right, I can continue:


    and we got the same result by the two sides.

    Please Advice,
    Dimitry Haritonov
  5. Nov 13, 2005 #4
    Dear Tom,

    are there any ideas ?

    Please Advice,
    Dimitry Haritonov
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook