[例6] 设函数 (x)=dfrac (x)(a+{e)^bx} 在 (-infty ,+infty ) 内连续,且 lim _(xarrow infty )f(x)=0, 则常数a,b-|||-满足 () .-|||-(A) lt 0 lt 0 (B) gt 0, gt 0-|||-(C) leqslant 0, gt 0 (D) geqslant 0, lt 0

7.设函数f(x)在 (-infty ,+infty ) 内可导,且 (x)=(e)^-2x+3lim _(xarrow 0)f(x) 则 (x)= ()()-

6.设 (x)=lim _(narrow infty )dfrac ({x)^2n-1+a(x)^2+bx}({x)^2n+1} 在 (-infty ,+inf

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

函数 (x)=lim _(tarrow 0)((1+dfrac {sin t)(x))}^dfrac ({x)(t)} 在 (-infty ,+infty )

(6) lim _(xarrow infty )dfrac (arctan x)(x)

(B) lim f(x)=0.-|||-(C) lim _(xarrow 1)f(x)=infty . D)limf(x)不存在,且 lim _(xarrow

[题目]-|||-设 lim _(xarrow infty )((dfrac {x+2a)(x-a))}^x=8 且 a≠0, 求常数a的值.

9.设函数f(x)在 (-infty ,+infty ) 内可导,且满足 (x)=f(x) (0)=m, 如果 (int )_(-1)^1dfrac (f(x)

设a,b为常数,且 lim _(xarrow infty )(sqrt [3](1-{x)^6}-a(x)^2-b)=0, 则 a= __ b= __ .

设函数f(x)在 (-infty ,+infty ) 上连续,且 (x)=(x)^2-x(int )_(0)^1f(x)dx, 则f(x)为 (-|||-