f(x)=x/(x-1)=(x-1+1)/(x-1)=1+1/(x-1)
2<=x<=5,则1<=x-1<=4
1/4<=1/(x-1)<=1.
所以,f(x)的最大值=1+1=2,最小值=1+1/4=5/4.
f(x)2