f(X+Y)=f(X)f(Y),且f(0)的导数存在,求证f `(x)=f(x)f `(0)

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f(X+Y)=f(X)f(Y),且f(0)的导数存在,求证f `(x)=f(x)f `(0)
f(X+Y)=f(X)f(Y),且f(0)的导数存在,求证f `(x)=f(x)f `(0)

f(X+Y)=f(X)f(Y),且f(0)的导数存在,求证f `(x)=f(x)f `(0)
根据导数定义,f'(x)=[f(x+t)-f(x)]/t (其中t是趋向于0的一个x的小分割),则 f'(x)=[f(x)*f(t)-f(x)]/t=f(x)*[f(t)-1]/t
由题意可知:f(x)=f(x+0)=f(x)*f(0),则有f(0)=1
那么f'(x)=f(x)*[f(0+t)-f(0)]/t=f(x)*f'(0)