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## Homework Statement

Simplify (x

^{-2}- y

^{-2}) / (x

^{-1}+ y

^{-1})

## Homework Equations

## The Attempt at a Solution

So I just factorised the numerator into x

^{-1}- y

^{-1}and x

^{-1}+ y

^{-1}. And was left with x

^{-1}- y

^{-1}as an answer. The text book gives (y - x) / (xy) as the answer (no working shown). So after some substitution I've realised my answer and the text book's are the same. But I would like to know how they got theirs and is it a simpler form of my answer?

And I read on the internet that polynomials with negative exponents are not called polynomials, is that true and what should they be called? Thanks a lot in advance :)