题目

函数y=－的反函数是A.y=x2+1(x∈R)                                               B.y=x2+1(x>0)C.y=x2+1(x≤0)                                                D.y=－x2+1(x≤0) 答案：解析:由y=－(x≥1)知y≤0，且x－1=(－y)2,即x=y2+1(y≤0).∴f－1(x)=x2+1(x≤0).答案:C

查看本题答案和解析