Răspuns:
1. x+y=2
2x+y=-5
y=2-x
2x+y=-5
y=2-x
2x+2-x=-5
y=2-x
x+2=-5
y=2-x
x=-7
y=2-7
x=-7
y=-5
x=-7
-2x+4y=10 /:2
3x+2y=1
-x+2y=5
3x+2y=1
2y=5-x
3x+2y=1
2y=5-x
3x+5-x=1
2y=5-x
2x+5=1
2y=5-x
2x=4
2y=5-x
x=2
2y=5-2
x=2
2y=3
x=2
y=3/2
x=2
y=1.5
x=2
2. x+y=7 /4
-4x+y=-3
4x+4y=28
-4x+y=-3
5y=25
x+y= 7
y=5
x+5=7
y=5
x=2
x+2y=3
2x+y=3
2y+x=3
y+2x=3 /-2
2y+x=3
-2y-4x=-6
-3x=-3
x+2y=3
x=1
1+2y=3
x=1
2y=2
x=1
y=1