导数的常见几种构造.doc

文档介绍：导数的常见构造 1 .对于???? xgxf''?,构造?????? xgxfxh??更一般地,遇到???? 0'??aaxf ,即导函数大于某种非零常数(若a =0 ,则无需构造), 则可构???? axxfxh?? 2 .对于???? 0''??xgxf ,构造?????? xgxfxh?? 3 .对于???? 0'??xfxf ,构造???? xfexh x? 4 .对于???? xfxf?' [或???? 0'??xfxf ] ,构造???? xe xfxh? 5 .对于???? 0'??xfx xf ,构造???? x xfxh? 6 .对于???? 0'??xfx xf ,构造???? x xfxh? 7 .对于???? 0 '?xf xf ,分类讨论: (1) 若?? 0?xf ,则构造???? xfxh ln?; (2) 若?? 0?xf ,则构造?????? xfxh?? ln ;