(tanx-sinx)/arctanx^3,求当x趋近于0时的极限.

tanx-sinx=tanx(1-cosx)~x·1/2·x^2=1/2·x^3arctan(a^3)~x^3lim(tanx-sinx)/arctanx^3=lim(1/2·x^3/x^3)=1/2