I'm struggling with this limit :
limx→0(xcotx)−1x2
It's in the 00 form, so I tried to use L'Hospital's rule:
limx→0((xcotx)−1)′(x2)′=limx→0cotx−xcsc2x2x=10−100
I'm not sure how to continue. I tried to derivate more, but only got similar expressions or 00. The result should be −13, so guess I'm doing something wrong. I would appreciate if somebody could tell me how to solve this one.
Thanks for help.
Answer
xcotx−1x2=xcosx−sinxx3⋅xsinx=(x−sinxx3+cosx−1x2)⋅xsinx
hence the limit of the RHS as x→0 is 16−12=−13.
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