题目

This is the moment a cleaner at a British university burst into tears after students raised $ 2,063 to send him to Jamaica on vacation to see family.Herman Gordon, who has worked at Bristol University for more than a decade, is described as “one of the most loved” members of its cleaning staff. He is so well liked that a group of students raised money to give him a holiday. A video shows a student hands an envelope of cash to the surprised Gordan with tears rolling down his cheeks. He wipes away tears with a cleaning cloth and hugs the student who gave it to him. Gordan said: “I want to 已知函数f（x）=x，g（x）=x4x-a．函数g（x）在（1，+∞）上单调递减．（Ⅰ）求实数a的取值范围；（Ⅱ）设函数h（x）=f（x）•g（x），x∈[1，4]，求函数y=h（x）的最小值．