(uvw)=u'ww+uv'w+uvw If(x)=fx)1(x)…fn(x +…+f1(x)f2(x)…fn(x) ∑If(x)A(x i=1k=1 ≠ ④作为(2)的特殊情况 若ν=c,则(cu)=c或|f(x=Cf(x) 即常数因子可以提到导数符号的外面 ∑4(x)=∑kf(x)(uvw) = uvw + uvw + uvw ( ) ( ); ( ) ( ) ( ) [ ( )] ( ) ( ) ( ) 1 1 1 2 1 2 1   =  = = =  + +   =  n i n k i k i k n n n i i f x f x f x f x f x f x f x f x f x    ④ 作为（2）的特殊情况 若v = c，则(cu) = cu 或 [Cf (x)] = Cf (x); 即常数因子可以提到导数符号的外面 [ ( )] ( ) 1 1 k f x k f x n i i i i n i  i  = =  = 