DragginMath: Multinomial Expansion

Algebra classes usually spend some time on Binomial Expansion: (a+b)ⁿ or (a+b)↑n, probably with an attendant discussion of Pascal’s Triangle. DragginMath has always been able to do this for specific n by evaluating (in this case, double-tapping ↑). DragginMath’s evaluator wasn’t explicitly designed to do this, but its general approach inherently does this and many more surprising and useful things. It even works for expanding multinomials: (a+b+c+…)↑n for specific n. But the results are messy, with equivalent terms like aab and aba scattered around for you to manually collect. Also, the results can quickly explode beyond the screen boundaries. This provides a good exercise in term collection if you’re looking for one, but it would be nice if there was a way to get results that were already collected.

Now there is: for any multinomial, drag the topmost + or − up onto ↑. And, consistent with DragginMath’s other distributive-like behaviors, you can ask it to stop expansion at specific places by dragging other non-top additive operators up onto ↑.