推论 (1)D∑f(x)=∑f(x (2)[C(x)=C(x); (3)[If(x)=f1(x)/2(x)…fn(x) +…+f1(x)f2(x)…fm(x) ∑∏f(x)/k(x) i=1k=1 k≠i (uvw)=uvw+uv'w+uvw推论 (1) [ ( )] ( ); 1 1   = =  =  n i i n i fi x f x (2) [Cf (x)] = Cf (x); ( ) ( ); ( ) ( ) ( ) (3) [ ( )] ( ) ( ) ( ) 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    (uvw) = u  v w+ uv  w+ uvw 