当X为有理数时F(X)=X,X为无理数时F(X)为0,问F(X)在X=0处是否可导

问题描述:

当X为有理数时F(X)=X,X为无理数时F(X)为0,问F(X)在X=0处是否可导

f(x) = xif x is rational number
= 0if x is ir-rational number
f(x) is discontinous over real line.
f(x) 在x=0处是不可导