题目内容
思路解析:由已知a2+=1,得2a2+b2=2,再逆用均值不等式将所求式凑出得证.
∵a≥0,b≥0,
∴a
答案:
A.y1y2≤x1x2 B.y1y2≥x1x2 C.y1y2>x1x2 D.y1y2<x1x2