lim(X趋向于0)(X平方/1-XtanX/1)写错了,是lim(X趋向于0)(1/x^2-1/XtanX)

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lim(X趋向于0)(X平方/1-XtanX/1)写错了,是lim(X趋向于0)(1/x^2-1/XtanX)

lim(X趋向于0)(X平方/1-XtanX/1)写错了,是lim(X趋向于0)(1/x^2-1/XtanX)
lim(X趋向于0)(X平方/1-XtanX/1)
写错了,是lim(X趋向于0)(1/x^2-1/XtanX)

lim(X趋向于0)(X平方/1-XtanX/1)写错了,是lim(X趋向于0)(1/x^2-1/XtanX)
lim(X趋向于0)(X平方/1-XtanX/1)
=lim(X趋向于0)(tanx-x)/(x^2tanx)
由无穷小量代换
=lim(X趋向于0)(tanx-x)/(x^3)
上下求导
=lim(X趋向于0)(1/(cosx^2)-1)/(3x^2)
再求导
=lim(X趋向于0)[-2/(cosx)^3]*sinx/(6x)
因为
lim(X趋向于0)(sinx)/(x)=1
原式=-1/3