常用的几种配元形式 (1)f(ax+b)dx=f(ax+b)d(ax+b) (2)|(x"ar≈1 f(x")dx n (3)[f(x2) dx三 f(x") dx x 万能凑幂法 4)f(sin x ) cos xdx= f(sin x)dsin x (5)If(cos x)sin xdx=- f(cos x)dcosx常用的几种配元形式: + =  (1) f (ax b)dx d(ax + b) a 1 =  − f x x x n n (2) ( ) d 1 n dx n 1 =  x x f x n d 1 (3) ( ) n dx n 1 n x 1 万 能 凑 幂 法 =  (4) f (sin x)cos xdx dsin x =  (5) f (cos x)sin xdx − dcos x