令(x)=lim _(xarrow infty )dfrac (1-{e)^-ax}(1+{e)^-ax},则(x)=lim _(xarrow infty )dfrac (1-{e)^-ax}(1+{e)^-ax}

lim _(xarrow +infty )((1+{e)^x)}^dfrac (1{x)};

极限lim _(xarrow infty )dfrac (1+{e)^x}(1-{e)^x}的结果是（ ）极限的结果是（）A.1B.-1C.0D.不存在

lim _(narrow infty )dfrac (1-{e)^-nx}(1+{e)^-nx}

6.20 求由曲线 _(1)(x)=lim _(xarrow +infty )dfrac (x)(1+{x)^2-(e)^ax} _(2)=dfrac (1)(

若lim _(xarrow 0)dfrac ({e)^2x-1}(tan ax)=-3-|||-__，则lim _(xarrow 0)dfrac ({e)^2x

3.求下列函数的极限.-|||-(1) lim _(xarrow infty )x((e)^dfrac (1{x)}-1);-|||-(2) lim _(xar

lim _(xarrow infty )x((e)^dfrac (1{2x)}-1)==

lim _(xarrow infty )(x)^2(sqrt (dfrac {1+{x)^2}({x)^2}}-1)= __

根据函数极限的定义证明:(1)lim _(xarrow infty )dfrac (1+{x)^3}(2{x)^3}=dfrac (1)(2) __;(2)li

4.求下列极限:-|||-(1) lim _(xarrow infty )(e)^dfrac (1{x)} :-|||-x→∞-|||-(3) lim _(xa