Răspuns :

Nastasa8id

a){x+y=5

{x-y=1

2x=6

x=3

{3+y=5

y=5-3

y=2

S{(3,2)}

b){x+y=4<=>3x=3=>x=1

{2x-y=-1

{x=1

{x-y=1

1-y=1

y=1-1

y=0

S={1,0)}

c){x-y=-3

{3x+y=11

4x=8

{x=2

{2.3+y=11

6+y=11

y=11-6

y=5

S={(2,5)}

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