from Francesca -
Some of the randomized problems do not use the product rule in both parts, some do. I would suggest to randomize so that part a does not require the product rule but has two terms with dy/dx, part b has the product rule but only one dy/dx
I have changed the code so that this feature is implemented. One line of the code can be uncommented to possibly produce harder problems as in the original version.
from Francesca - Some of the randomized problems do not use the product rule in both parts, some do. I would suggest to randomize so that part a does not require the product rule but has two terms with dy/dx, part b has the product rule but only one dy/dx