Question

设集合U={(x,y)|x∈R,y∈R},A={(x,y)|2x-y+m＞0},B={(x,y)|x+y-n≤0},则点P(2,3)∈A∩(B)的充要条件是(    )

A.m＞-1且n＜5                           B.m＜-1且n＜5

C.m＞-1且n＞5                           D.m＜-1且n＞5

Answer 1

答案：A由P(2,3)∈A知4-3+m＞0即m＞-1,

而B={(x,y)|x+y-n＞0},P(2,3)∈B得n＜5.