例7设y=x2e2,求 解设u=e2,p=x2,则由菜布尼兹公式知 y)=(e2))x2+20(e2)"9).(x2y 20(20-1)/2x8 e (x2)"+0 2 =20e2x·x2+20.2le2x.2x 20·19 182x 十 2 2 =2e2(x2+20x+95)例 7 , . 2 2 (20) y x e y 设 = x 求 解 设u = e 2 x , v = x2 ,则由莱布尼兹公式知 ( ) ( ) 0 2! 20(20 1) ( ) 20( ) ( ) 2 (18) 2 (20) 2 (20) 2 2 (19) 2   + − + =  +   e x y e x e x x x x 2 2 2! 20 19 2 20 2 2 18 2 20 2 2 19 2  + =  +   x x x e e x e x 2 ( 20 95) 20 2 2 = e x + x + x