推论 u1(x)±u2(x)土…±un(x) l(x)±u2(x)±…±un(x) 2.[1(x)l2(x)…un(x) ∑(x)a2(x)“(x)…un(x) 3.[C(x)=Cu(x); vX v(x v X Economic-mathematics 31-10 Wednesday, February 24 2021Economic-mathematics 31 - 10 Wednesday, February 24, 2021 推论 . ( ) ( ) ] ( ) 1 4. [ 2 v x v x v x   = − 3. [Cu(x)] = Cu(x); ( ) ( ) ( ) 1. [ ( ) ( ) ( )] 1 2 1 2 u x u x u x u x u x u x n n =             = =   n i i n n u x u x u x u x u x u x u x 1 1 2 1 2 [ ( ) ( ) ( ) ( )] 2. [ ( ) ( ) ( )]   