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#8578f491-b92b-433c-95d0-6d34f5e08ada中等解答题极值点偏移导数

10.已知函数f(x)=xex(xR)f(x)=xe^{-x}(x\in R)
(Ⅰ)求函数f(x)f(x)的单调区间及极值;
(Ⅱ)求证:当x>1x>1时,f(x)>f(2x)f(x)>f(2-x)
(Ⅲ)如果x1x2x_{1}\ne x_{2},且f(x1)=f(x2)f(x_{1})=f(x_{2}),求证:x1+x2>2x_{1}+x_{2}>2