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rezolvati prin metoda grafica sistemul de ecuatie :
x+y=4
3x+y=6

x+y=1
2x+y=5

x-y=2
2x-2y=-2

3x+6y=-3
4x+8y=2

2x-y=1
4x-2y=2

2x-4y=10
3x-6y=15


Răspuns :

x+y=4=>y=4-x
3x+y=6=>3x+4-x=6=>2x=2=>x=1   y=4-1=3

x+y=1=>y=1-x
2x+y=5=>2x+1-x=5=>x+1=5=>x=4        y=1-4=-3

x-y=2=> (1)
2x-2y=-2=>2(x-y)=-2=>x-y=-1=>2=-1 fals=>solutia e multimea vida

3x+6y=-3=>3(x+2y)=-3=>x+2y=-1 
4x+8y=2 =>2(2x+4y)=2=>2x+4y=1=>2(x+2y)=1=>2*(-1)=1=>-2=1 fals =>solutia e multimea vida

2x-y=1=>-y=1-2x=>y=2x-1
4x-2y=2=>4x-4x+2=2=>2=2  S=R

2x-4y=10=>2(x-2y)=10=>x-2y=5
3x-6y=15=>3(x-2y)=15=>x-2y=5 =>S=R