Question

Rezolvati sistemul de ecuații x-y=-1 3x+2y=-7

Answer 1

[tex] \left \{ {{x-y=-1 | *2} \atop {3x+2y=-7}} \right. \\ \\ \left \{ {{2x-2y=-2} \atop {3x+2y=-7}} \right. \\ \\ 5x=-9=\ \textgreater \ x=- \frac{9}{5} \\ \\ - \frac{9}{5} -y=-1 \\ \\ - \frac{9}{5} +1=y=\ \textgreater \ y=- \frac{4}{5} [/tex]

Answer 2

x-y=-1 /X2

3x+2y=-7

rezulta

2x-2y=-2  adunam si rezulta 2x-2y+3x+2y=-9 rezulta 5x=-9; x=-9/4 inlocuim x in

3x+2Y=-7    ecuatia x-y=-1  si rezulta -9/4 -y=-1

rezulta -y=9/4-1;  -y=5/4 rezulta y=-5/4 proba -9/4-(-5/4)=-1 ; -9/4+5/4=-1;

-4/4=-1 rezulta -1=-1 deci este corecta solutia