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> Evaluate $\lim\_{x \to 0+} \frac{x-\sin x}{(x \sin x)^{3/2}}$
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This is an exercise after introducing L'Hopital's rule. I directly apply L'Hopital's rule three times and it becomes more and more complex. So I try to substitute $t=\sqrt x$ but there's a square root remained in the denominator $t^3 (sin(t^2))^{3/2}$,apply L'Hopital's rule three times or more I still can't solve it. So I think maybe I have to write $t=\sqrt{x \sin x}$ ,but I can't find a way to convert $x- \sin x$ to a function about $t$ . 

Thanks in advance.