Well, as you see, it works. And (I presume) they would like you think about the fact that throwing the same equation at Google does nothing useful (inexplicably, the first result was a page about BSD).
But I wonder how many users of this feature will be familiar with the rules of operator precedence? I admit I read it as:
x-3
--- = ... << I can't format it right but you get the idea
x-1
After testing it with Google, I went to Alpha, which (unsurprisingly) handled it with aplomb, giving it to me with proper notation as well and making me aware of my mistake. So I tried it as (x-3) / (x-1) = (x-4) / (x-5), which Alpha also handled with Aplomb (11/3 if you are lazy).
However, inputing the latter into Bing (without or without spaces for padding) gave no calculation or result, but just a bunch of (mostly unrelated) search results. Seems rather counter-productive on MS's part.
Apologies if this is excessively trivial.