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)