设函数f(x)可微,则lim(h→0)[ f2(x+h)-f2(x)]/h

问题描述:

设函数f(x)可微,则lim(h→0)[ f2(x+h)-f2(x)]/h

  记G(x)=f²(x)
则lim(h→0)[ f2(x+h)-f2(x)]/h
=lim(h→0)[ G(x+h)-G(x)]/h
=G'(x)
=2f(x)f'(x)
' 指的是函数的微分