Question

若集合A={(x,y)|x+y=1}，映射f：A→B在f作用下，點（x,y)的象是(2^x,2^y),則集合B是（    ）

A.{(x,y)|x+y=2,x＞0,y＞0}                      B.{(x,y)|xy=1,x＞0,y＞0}

C.{(x,y)|xy=2,x＜0,y＞0}                        D.{(x,y)|xy=2,x＞0,y＞0}

Answer 1

解析：∵x+y=1,

∴2^x·2^y=2^x+y=2.

故選D.

答案：D.