Mark M. answered 08/04/18
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Retired math prof. Calc 1, 2 and AP Calculus tutoring experience.
limx→0 [1/x - cotx] = limx→0 [1/x - cosx/sinx]
= limx→0 [(sinx - xcosx) / (xsinx)] (0/0 form)
= limx→0 [(cosx - cosx +xsinx) / (sinx + xcosx)] (By L'Hopital's Rule)
= limx→0 [xsinx / (sinx + xcosx)] (Still has the form 0/0)
= limx→0 [(sinx + xcosx) / (cosx + cosx - xsinx)] (By L'Hopital's Rule)
= 0 / 2 = 0