Problem set 1 - find the derivative of sinx/x. There is an answer, which is easy enough to get to, but it is not clear to me that the derivative of this function exists at zero, and the answer key does not specify a restricted domain for f'(x). Evaluating f'(0) actually seems to give an indeterminate form... help?

Question

Problem set 1 - find the derivative of sinx/x.  There is an answer, which is easy enough to get to, but it is not clear to me that the derivative of this function exists at zero, and the answer key does not specify a restricted domain for f'(x).  Evaluating f'(0) actually seems to give an indeterminate form... help?

anonymous · Answer

It's good that you're thinking about these details. True, f' is undefined at x=0, but f is also undefined at x=0. We don't bother stating a restricted domain for f' because it's defined for all values within the domain of f.

anonymous · Answer

Okay, thanks.