解
/2x+y-3/+√(x-3y-5)²=0
/2x+y-3/+/x-3y-5/=0
∵/2x+y-3/≥0
/x-3y-5/≥0
∴2x+y-3=0 (1)
x-3y-5=0 (2)
(2)×2得：2x-6y-10=0 (3)
(1)-(3)得：7y+7=0
∴y=-1
∴x=2
∴xy=2×(-1)=-2