x+y=3则2x+2y=6
(2x+2y)+(5x-2y)=6+1
2x+2y+5x-2y=7
7x=7
x=1
x+y=3 则y=2
或x+y=3.(1)
5x-2y=1.(2)
(1)+(2)得出6x-y=4.(3)
(1)+(3)得出7x=7
x=1,y=2