Lingling wants ____ (go) to the US.
(Ⅰ)若函数y=f(x)在区间1,+∞)上是单调递增函数,求实数a的取值范围;
(Ⅱ)若函数y=f(x)有两个极值点x1,x2,且x1<x2,求证: 0<f(x2)x1<−12+ln2 .