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#956425e0-ac75-4eb6-83b9-4705eb51c576中等解答题极值点偏移导数

9.已知函数f(x)=x1exf(x)=\frac{x-1}{e^x}
(1)求函数f(x)f(x)的单调区间和极值;
(2)若函数y=g(x)y=g(x)对任意xx满足g(x)=f(4x)g(x)=f(4-x),求证:当x>2x>2f(x)>g(x)f(x)>g(x)
(3)若x1x2x_{1}\ne x_{2},且f(x1)=f(x2)f(x_{1})=f(x_{2}),求证:x1+x2>4x_{1}+x_{2}>4