a)
x-y=0
5x+y=1
x=y
5y+y=1
x=y
6y=1
x=1/6
y=1/6
b)
4x-y=1
8x-2y=3
y=4x-1
8x-2(4x-1)=3
y=4x-1
8x-8x+1=3
y=4x-1
1=3
In sistemul acesta, cred ca in enunt este o greseala undeva
c)
2x+3y=1
2x-5y=9
2x=1-3y
1-3y-5y=9
2x=1-3y
-8y=9-1
2x=1-3y
-8y=8
2x=1-3y
y=-1
2x=1-3*(-1)
y=-1
2x=1+3
y=-1
2x=4
y=-1
x=2
y=-1