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February 1st, 2011, 02:05 PM  #1 
Newbie Joined: Sep 2010 Posts: 24 Thanks: 0  Need help with 3exam questions ..
I need these three questions answered please :$ 1.Is there a number such that the produckt of its digits is equal with 465 2.Prove that a set of all positiv integers divisble by 5 is a countable set 3. Prove that an empty set is a subset of each other set (Sry I didnt know where to post it) THANK YOU! 
February 1st, 2011, 02:45 PM  #2  
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Re: Need help with 3exam questions .. Quote:
2. Use the function n = 5m to show that there is a multiple of 5 for every integer. 3. Use the definition of subset  
February 1st, 2011, 02:55 PM  #3 
Newbie Joined: Sep 2010 Posts: 24 Thanks: 0  Re: Need help with 3exam questions ..
I need them solved step by step brother :$ I'm so sorry, My friend needs them for tomorrow 
February 1st, 2011, 03:27 PM  #4  
Global Moderator Joined: Nov 2009 From: Northwest Arkansas Posts: 2,766 Thanks: 4  Re: Need help with 3exam questions .. Quote:
Step 2: Devise a plan Step 3: Carry out the plan Step 4: Look back (check) If your plan is to get us to do your ("friend's") work, then you need a new plan. What's wrong with the advice you've already been given? The product of (some numbers) = 465. What is the prime factorization of 465? You should be able to figure this out. What is meant by a "digit"? Can a digit be negative? Can 37 be a digit? Empty set subset of every (other) set. What does it mean for A to be a subset of B? You must have a definition! By "must", I mean "I'm positive that you have enough information to work with". A subset B <=> (x in A => x in B) Replace A with the empty set, and use what you know about the empty set. You should have a false hypothesis. Google that if you don't know what that means.  
February 2nd, 2011, 08:02 AM  #5  
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Re: Need help with 3exam questions .. Quote:
 

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