(3)函数u(x)v(x在x可导,且 「u(x)·w(x)=l(x)·v(x)+u(x)·v(x) (4)函数“(x) 在x可导,且 (x) u(x) u(x) v(x-u(x).v(x) = vlr v(x)2 v(x)≠0) 2021/2/202021/2/20 4 (3) 函数[u(x) v(x)]在x可导,且 [u(x) v(x)] = u(x) v(x) + u(x) v(x) 函 数 在 可 导,且 ( ) ( ) (4) x v x u x 2 [ ( )] ( ) ( ) ( ) ( ) ] ( ) ( ) [ v x u x v x u x v x v x u x   −    = ( v(x)  0 )