A.4                              B.3                              C.2                              D.1               

已知变量x、y满足条件则x+y是最小值是

A．4                            B．3                            C．2                            D．1

A.2      B.5                       C.6                              D.8                                    

已知变量x、y满足条件则x+y的最大值是(    )。

A．2                B．5                C．6                D．8