先用等价无穷小：e^(2x) -1 2x原式 =lim (sinx - tanx) / (2x^3)=lim [cosx - (secx)^2] / 6x^2 【罗比达法则】=lim [(cosx)^3 -1] / [6x^2 (cosx)^2)]=lim (cosx -1)[(cosx)^2 +cosx +1] / [6x^2 (cosx)^2) ]=lim [...