6y+6x=5xy
6=xy
6x+6y=5*6
x+y=5
x=5-y
把x=5-y代入xy=6
(5-y)y=6
y方-5y+6=0
(y-2)(y-3)=0
y1=2
y2=3
把这二个值代入x+y=5
x1=3
x2=2