已知y=f(x)是偶函数,当x>0时,f(x)=x+
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,当x∈[-3,-1]时,n≤f(x)≤m恒成立.
(Ⅰ) 若a=1,求m-n的最小值;
(Ⅱ) 求m-n的最小值g(a);
(Ⅲ)当a>16时,是否存在k∈(1,2],使得不等式f(k-cosx)≥f(k
2-cos
2x)对任意x∈R恒成立?若存在,求出实数k的范围;若不存在,请说明理由.
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