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Rezolvati prin metoda substitutiei :
2(x+y)-3y=-11
-4x+3(x+y)=18


Răspuns :

2x+2y-3y=-11
2x-y=-11 |+y
2x=y-11 |+11
y=2x+11



-4x+3x+3y=18
3y-x=18
3•(2x+11)-x=18
6x+33-x=18 |-33
5x= -15 |:5
x= -3.

y=2x+11=2•( -3)+11= -6+11=5.