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问题: 求极限的问题

lim (x趋于0):cot x (1/sinx -1/x)
希望有过程!

解答:

lim(x→0) cot x (1/sinx -1/x)

=lim(x→0) cosx(x-sinx)/(x×sinx×sinx)

=lim(x→0) (x-sinx)/(x^3)

=lim(x→0) (1-cosx)/(3x^2)

=lim(x→0) (1/2×x^2)/(3x^2)=1/6