19、单选 反常积分 (int )_(0)^+infty dfrac (1)(1+x+{x)^2}dx= __-|||-(3分-|||-A) .dfrac (sqrt {3)}(9)pi -|||-B .dfrac (sqrt {3)}(18)pi -|||-C 不存在-|||-D .dfrac (2sqrt {3)}(9)pi

(int )_(-infty )^+infty (x)^2(e)^-a(x^2)dx=dfrac (1)(2)sqrt (dfrac {pi )({a)^3}}

证明反常积分(int )_(1)^+infty dfrac (sin {x)^3}(sqrt {{x)^3}}dx绝对收敛.证明反常积分绝对收敛.

计算积分(int )_(dfrac {1)(2)}^dfrac (3{2)}dfrac (dx)(sqrt {|x-{x)^2|}}.(本题满分6分)计算积分.

1.计算下列定积分:-|||-(1) (int )_(dfrac {pi )(3)}^pi sin (x+dfrac (pi )(3))dx ;-|||-(2)

求不定积分int dfrac (1)(2x)sqrt (ln x)dx=（）.int dfrac (1)(2x)sqrt (ln x)dx=int dfrac

2.计算下列定积分:-|||-(1) (int )_(dfrac {pi )(3)}^pi sin (x+dfrac (pi )(3))dx;-|||-(2)

求下列不定积分:-|||-(1) int dfrac (1)(5x-3)dx ;-|||-(3) int dfrac (1)(sqrt {x+1)+sqrt (

(int )_(-dfrac {pi )(2)}^dfrac (pi {2)}dfrac (|x|sin x)(1+{cos )^3x}dx=(int )_(-

求定积分(int )_(1)^sqrt (3)dfrac (1)({x)^2sqrt (1+{x)^2}}dx求定积分

(3) (int )_(0)^dfrac (pi {4)}dfrac (x)(1+cos 2x)dx= () .-|||-(A) dfrac (pi )(8)+