P and Q represent different positive integers. Find all values of both P and Q such that the product of the product of P and Q and the difference of P less Q is equal to 100737. In other words, .
Source: mathcontest.olemiss.edu 10/11/2010
Solution
First, let’s write the prime factorization of .
The problem asks us to rewrite as a product of three factors, i.e. .
Example 1:
Example 2:
In Example 1, if we let and , then , so this is not a solution.
In Example 2, if we let and , then , so this is not a solution.
Notice that the factors are always odd, because there is no in the prime factorization of .
In Example 1, and . In Example 2, and .
Thus, the third factor must be odd, but this is not possible because when you subtract two odd numbers you always get an even number.
We conclude that there are no different positive integers and such that .
We can check our answer by looking at the list of all possible groups of three factors below:
3 |
3 |
11193 |
100737 |
3 |
7 |
4797 |
100737 |
3 |
9 |
3731 |
100737 |
3 |
13 |
2583 |
100737 |
3 |
21 |
1599 |
100737 |
3 |
39 |
861 |
100737 |
3 |
41 |
819 |
100737 |
3 |
63 |
533 |
100737 |
3 |
91 |
369 |
100737 |
3 |
117 |
287 |
100737 |
3 |
123 |
273 |
100737 |
7 |
9 |
1599 |
100737 |
7 |
39 |
369 |
100737 |
7 |
117 |
123 |
100737 |
9 |
13 |
861 |
100737 |
9 |
21 |
533 |
100737 |
9 |
39 |
287 |
100737 |
9 |
41 |
273 |
100737 |
9 |
91 |
123 |
100737 |
13 |
21 |
369 |
100737 |
13 |
63 |
123 |
100737 |
21 |
39 |
123 |
100737 |
21 |
41 |
117 |
100737 |
39 |
41 |
63 |
100737 |