I'm struggling with this limit :
$$ \lim_{x\to 0} {(x \cot x)-1 \over x^2} $$
It's in the $0\over0$ form, so I tried to use L'Hospital's rule:
$$ \lim_{x\to 0} {((x \cot x)-1)' \over (x^2)'} = \lim_{x\to 0} { \cot x - x \csc^2 x \over 2x} = {\frac 10 - \frac 10 \over 0} $$
I'm not sure how to continue. I tried to derivate more, but only got similar expressions or $\frac 00$. The result should be $-\frac13 $, so guess I'm doing something wrong. I would appreciate if somebody could tell me how to solve this one.
Thanks for help.
Answer
$$\frac{x\cot x-1}{x^2}=\frac{x\cos x-\sin x}{x^3}\cdot\frac{x}{\sin x}=\left(\frac{x-\sin x}{x^3}+\frac{\cos x-1}{x^2}\right)\cdot\frac{x}{\sin x}$$
hence the limit of the RHS as $x\to 0$ is $\frac{1}{6}-\frac{1}{2}=\color{red}{-\frac{1}{3}}$.
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