Question

ajuda PF x-3y=9
-x-3y=15



essa aqui tambem

x-y=9
x+y=19

Answer 1

x-3y=9
-x-3y=15
---------
-6y=24.(-1)
y=-4
x-3(-4)=9

x+12=9
x=-3
S={(-3;-4)}

x-y=9
x+y=19
----------
2x=38
x=19

19-y=9
-y=-10.(-1)
y=10

S={(19;10)}