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April 27, 2015

April 27, 2015

Posted by **Candice** on Wednesday, July 15, 2009 at 11:06pm.

Thank u :)

- math -
**Reiny**, Thursday, July 16, 2009 at 9:17amthis is an example of what is called a Diophantine equation.

There are several ways to solve these, I use a method involving continued fractions, but it is too messy to explain here.

Let's use a "common sense" method.

Consider the intercepts,

We have (0,401) and (1002.5,0) but neither of these would be allowed since you are looking for positive integers.

The closest point to the y-intercept that would work is

(1000,1)

Now the slope of the line is -2/5, which means that for every increase of 2 for a y, we need a decrease of 5 for the x.

so possible points would be

(995,3), (990,5), (985,7) etc. until we get close to the x-intercept

We could then have 1000/5 or 401 "jumps" to get to (5,399)

so the points from smallest x to largest x would be

(5,399), (10,397) ... (995,3), (1000,1)

so there are 401 points which are solutions, using only positive integers.