How many pairs of positive fractions with denominators 3 and 5 have a sum of 2 1/15?
Note: Assume the numerators are integers.
New Task: Repeat the problem, but remove the restriction "positive."
New New Task: How many pairs of positive fractions with denominators A and B have a sum of N/(AB), for A,B, N nonzero? (Also, can you find A and B such that either no pairs or a finite number of pairs exist?)
Source: Adapted from G. Merriman's To Discover Mathematics, 1942, p. 367
Hint: You can try some possible numerators....but, how can you know if you have them all?
How can you attack the problem in general terms...think, algebra to the rescue?
Solution Commentary: You can play with this on your own....but ideas such as a linear equation aA+bB = n should eventually appear.
Now, where have you seen this before...and how was that "brief meeting" helpful?