江画工太猩院 limr u(r+h)-u(x v(x+h) h vlx+h x +(x). lim u(rt h -u(x limb(x+ h h-0 h-0 +以(x)lim v(x+h)-v(r h->0 h u(x)·v(x)+(x)v(x)江西理工大学理学院 ] ( ) ( ) ( ) ( ) ( ) ( ) lim[ 0 h v x h v x u x v x h h u x h u x h + − + ⋅ ⋅ + + − = → = u ′(x)⋅ v(x) + u(x)⋅ v′(x) h v x h v x u x v x h h u x h u x h h h ( ) ( ) ( ) lim lim ( ) ( ) ( ) lim 0 0 0 + − + ⋅ ⋅ + + − = → → →