20.-|||-(int )_(0)^3(e)^-sqrt (1-x)dx=( ) () 。-|||-A .(e)^-1-6(e)^-2 I-|||-B .(e)^-1+4(e)^-2-|||-C (e)^-1-4(e)^-2-|||-D .(e)^-1+6(e)^-2 ;

()-|||-A (X)=0, E(Y)=2-|||-B (x)=2, E(Y)=0-|||-C (X)=3, E(Y)=1-|||-D (x)=1 E(Y)=

( 单选题 ) int dfrac ({e)^x}(1+{e)^2x}dx=_________int dfrac ({e)^x}(1+{e)^2x}dx=int

(8) lim _(xarrow 0)dfrac ({e)^3x-(e)^2x-(e)^x+1}(sqrt [3]{(1-x)(1+x))-1} .

(int )_(1)^(e^2)dfrac (ln x)(sqrt {x)}dx= __

[例3] (int )_(0)^+infty dfrac (x{e)^-x}({(1+{e)^-x)}^2}dx

(5) (int )_(0)^ln 2sqrt ({e)^x-1}dx

(int )_(0)^+infty dfrac (x{e)^-x}({(1+{e)^-x)}^2}dx= ()-|||-__

int((1)/(sqrt(x))-e^x)dx= ().A. $\sqrt{x}-e^{x}+C$B. $2\sqrt{x}-e^{x}+C$C. $\sqr

[题目]-|||-求下列极限:-|||-lim _(xarrow 0)dfrac ({e)^3x-(e)^2x-(e)^x+1}(sqrt [3]{(1-x)(

求下列极限:-|||-__-|||-(8) lim _(xarrow 0)dfrac ({e)^3x-(e)^2x-(e)^x+1}(sqrt [3]{(1-x