问题 选择题 若|x+y-3|+(x-y+5)2=0,则xy=( )A.-4B.4C.3D.5 答案 ∵|x+y-3|+(x-y+5)2=0,∴x+y-3=0x-y+5=0,解得:x=-1y=4,∴xy=-1×4=-4.故选:A.