2nd derivatives on TI 36 Pro

[lrdheat]

Alas, while this works for finding 2nd derivative = for functions like sin(x) or sin(x)^2, I get an invalid domain error for functions such as x^4-4*x^3. If anyone figures out why this is the case, please post.

I have not run into a problem yet with finding zeros for first derivatives to find a max or min of f(x) for any function that takes less than 80 characters to enter.