Hmm, I thought they had fixed that issue completely; hence, I mentioned the removal of the capability. I'll look into verifying that, too, if and when I have spare time.
It's fine. You're right, in general, on the binomial expansion, but afair, the first term would still be 1x^3y^0, or x^3.

I had to do the addition anyways just to be sure I was doing it right. It was the long way around.
Wyatt Hebert