已知f(x)=x/(1+e^(1/x))(x≠0),0(x=0), 求点x=0处的f'+(0),f
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咨询记录 · 回答于2021-10-01
已知f(x)=x/(1+e^(1/x))(x≠0),0(x=0), 求点x=0处的f'+(0),f
f'-(0)=lim[x→0-] [f(x)-f(0)]/x=lim[x→0-] [x/(1+e^(1/x))] / x=lim[x→0-] 1/(1+e^(1/x))=1注:x→0-时,1/x→-∞,e^(1/x)→0f'+(0)=lim[x→0+] [f(x)-f(0)]/x=lim[x→0+] [x/(1+e^(1/x))] / x=lim[x→0+] 1/(1+e^(1/x))=0注:x→0+时,1/x→+∞,e^(1/x)→+∞