Key hint missing. Wording in solution should be improved.

The key hint, to use McLaurin series is missing. The hint about sin(y)/y should be a second hint rather. In fact, it would be less confusing if it was y/sin(y) instead. The solution with L'Hospital does not work at all, due to the chain rule in the denominator. Hence the presented solution is not "the quickest way" but the only way to solve this.

Thanks, please feel free go ahead to make the changes you envisioned. I agree enough to let you take over. I don't have time to implement it myself now.

The L'Hospital rule does invoke chain rule and possibly "impossibly-many" complications, however, a simple call to an algebra system gives the denominator to be something like (smaller terms) + 120*x*cos(x^5). So it either requires an inhuman length of calculation or an understanding to ignore "higher order terms" which is not probably not available to most students. (The numerator is simple though, and 4 differentiations suffice to end the case).

So I agree we should simply omit it and say it's "impossible", in some sense.

Thanks, please feel free go ahead to make the changes you envisioned. I agree enough to let you take over. I don't have time to implement it myself now.

The L'Hospital rule does invoke chain rule and possibly "impossibly-many" complications, however, a simple call to an algebra system gives the denominator to be something like (smaller terms) + 120*x*cos(x^5). So it either requires an inhuman length of calculation or an understanding to ignore "higher order terms" which is not probably not available to most students. (The numerator is simple though, and 4 differentiations suffice to end the case).

So I agree we should simply omit it and say it's "impossible", in some sense.

Much better, thank you Christina.