高数课程妥媒血课件 镭理工大理>> 例3求 dx x(1+2Inx) 解 x(1+2nx) 1+2Inx d(n x d(+2In x) 2 1+2Inx u=1+2Inx Inu+C=-In(1+2Inx)+C 2 Http://www.heut.edu.cn例3 求 . (1 2ln ) 1 dx x x  + 解 dx x x  (1+ 2ln ) 1 (ln ) 1 2ln 1 d x x  + = (1 2ln ) 1 2ln 1 2 1 d x x + + =  u = 1+ 2ln x  = du u 1 2 1 = lnu + C 2 1 ln(1 2ln ) . 2 1 = + x + C