下列公式错误的是A.int dfrac (1)({a)^2+(x)^2}dx=arctan dfrac (x)(a)+C,(aneq 0)B.int dfrac (1)({a)^2+(x)^2}dx=arctan dfrac (x)(a)+C,(aneq 0)C.int dfrac (1)({a)^2+(x)^2}dx=arctan dfrac (x)(a)+C,(aneq 0)D.int dfrac (1)({a)^2+(x)^2}dx=arctan dfrac (x)(a)+C,(aneq 0)

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

int dfrac (5x-1)({x)^2-x-2}dx= (.A.int dfrac (5x-1)({x)^2-x-2}dx= (B.int dfrac (

(int )_(0)^1arctan dfrac (x)(2)dx=()(int )_(0)^1arctan dfrac (x)(2)dx=()(int )_(

dfrac (dy)(dx)=(x)^2+(y)^2 B . dfrac (dy)(dx)=(x)^2+(y)^2 C .dfrac (dy)(dx)=(x)^

.(int )_(-2)^2dfrac (x+|x|)(2+{x)^2}dx= __ .

(int )_(-2)^2dfrac (x+|x|)(2+{x)^2}dx=

(9) int dfrac (x{e)^arctan x}({(1+{x)^2)}^dfrac (3{2)}}dx ;

(5) int dfrac (arctan x)(1+{x)^2}dx= __

(int )_(0)^dfrac (pi {4)}dfrac (x)(1+cos 2x)dx=( ) .(int )_(0)^dfrac (pi {4)}dfr

[题目]计算 (int )_(1)^+infty dfrac (arctan x)({x)^2}dx