设函数x,y满足x2-2xy-1=0,则x-y的取值范围是_.
问题描述:
设函数x,y满足x2-2xy-1=0,则x-y的取值范围是______.
答
∵x2-2xy-1=0
∴(x-y)2=1+y2≥1
则x-y≥1或x-y≤-1
故x-y的取值范围是(-∞,-1]∪[1,+∞)
故答案为:(-∞,-1]∪[1,+∞)