CUNY Math Challenge Blog

Solutions, Resources, Further Information & Discussion

Round 1: Problem 5

with one comment

Begin with a set of distinct positive integers. A new positive integer may be constructed and added to the set so long as it has the form (a+b)/(a-b) where a and b are already in the set. (For example, if 9 and 6 are already in the set, then the number 5 may be added.) The original set of integers is called “prolific” if every positive integer can eventually be constructed and added to the set. What is the smallest size that a prolific set can have? Prove your answer.

Advertisements

Written by Administrator

February 18, 2010 at 23:28

Posted in Round 1

One Response

Subscribe to comments with RSS.

  1. Why are these problems SO easy? The name says “challenge”…

    ME

    March 26, 2010 at 13:02


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: