When the line L passes through the point P (2,1) and the area of the triangle enclosed by the positive half axis of the two coordinate axes is the smallest, the equation of the line L is obtained

When the line L passes through the point P (2,1) and the area of the triangle enclosed by the positive half axis of the two coordinate axes is the smallest, the equation of the line L is obtained

x+y=3,
x>0
y>0
xy