[Math] How to say that something rises with the fall of something else

Question

I want to write in a math article that one parameter is going up when other is falling. These parameters are linked. What is a formal way of writing it?
"Parameter A is rise with the fall of parameter B"?

Answer 1

Going from a hunch, I would suggest "inversely proportional." If you are writing this article for a school or class you can probably get a great answer from a local math teacher or professor.

Edit: Okay, I guess I should have known that there was a technical definition of "inversely proportional." Wikipedia has a quick description, as do the comments here.

For example, the time taken for a journey is inversely proportional to the speed of travel; the time needed to dig a hole is (approximately) inversely proportional to the number of people digging.

So, inversely proportional is one type of rising with the fall of something else. A more generic term will be more appropriate.