V(30) int dfrac (dx)({e)^x+(e)^-x} ;

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

设 int dfrac (f(x))(x)dx=(e)^x+C ，则int dfrac (f(x))(x)dx=(e)^x+Cint dfrac (f(x))(

int dfrac ({e)^x}({2)^x}dx;

例28 计算下列积分:-|||-(1) (int )_(0)^2dfrac (x)({e)^x+(e)^2-x}dx ;

int dfrac (x+{x)^3}(1+{x)^4}dx

设 (x)=(e)^-x, 则 int dfrac (f(ln x))(x)dx= .(x)=(e)^-x, 则 int dfrac (f(ln x))(x)

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

[题目]求 int dfrac (arctan {e)^x}({e)^2x}dx

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

(int )_(e)^+infty dfrac (dx)(x{ln )^2x}= __