dfrac (2x)(1+{x)^2}

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

(2) lim _(xarrow 0)[ dfrac (1)(ln (1+{tan )^2x)}-dfrac (1)(ln (1+{x)^2)}]

(2) lim _(xarrow 0)[ dfrac (1)(ln (1+{tan )^2x)}-dfrac (1)(ln (1+{x)^2)}]

.int dfrac (1+{cos )^2x}(1+cos 2x)dx

int dfrac (sin x)(1+{cos )^2x}dx=-|||-__

(int )_(-dfrac {pi )(2)}^dfrac (pi {2)}((cos )^2x+dfrac (xcos x)(1+{cos )^2x})dx

()-|||-(2) (int )_(-infty )^+infty dfrac (2x)(1+{x)^2}dx=lim _(aarrow +infty )(i

求极限 lim _(xarrow 0)dfrac (ln (1+{x)^2)-ln (1+(sin )^2x)}(x{sin )^3x}

讨论下列函数的有界性：(1) (x)=dfrac (x)(1+{x)^2}-|||-(2) (x)=dfrac (1+{x)^2}(1+{x)^4}讨论下列函数

int dfrac ({x)^3}({(1+{x)^2)}^2}dx=A.int dfrac ({x)^3}({(1+{x)^2)}^2}dx=B.int df