My guess is that if a line passes through two integer lattice points, then it will always contain infinite integer lattice points.
So in general given a line, $$ ax+by+c=0 $$ How many integral $a$ and $b$ satisfy it?
For more context, this idea popped up as I was solving the following question
In triangle ABC, the coordinates of A and B are respectively $(2,3)$ and $(8,10)$. It is known that C also has integer coordinates. The minimum possible area of triangle ABC is?
I solved it to get $0$ as the minimum area (which is correct). I luckily found another integer point on the line AB as $(-4,-4)$. Hence the area is $0$.
Another small doubt, I had read somewhere that such a rule about integer points can easily be generalized to rational points by scaling the axes. Can someone elaborate on this? Is it true?