a-b=根号2-1-2根号2+1=-根号2b＞ab-c=2根号2-1-根号6+1=2根号2-根号6b＞c所以，b＞c＞a
a-b=根号2-1-2根号2+1=-根号2b＞ab-c=2根号2-1-根号6+1=2根号2-根号6b＞ca-c=根号2-根号6<0c＞a所以，b＞c＞a
