[tex] \left \{ {3x+y=8} \atop {x+2y=-6}} \right. \\ \\ \left \{ {y=8-3x} \atop {x+2(8-3x)=-6}} \right. \\ \\ \left \{ {y=8-3x} \atop {x+16-6x=-6} \right. \\ \\ \left \{ {y=8-3x} \atop {16+6=5x} \right. \\ \\ \left \{ {y=8-3x} \atop {x= \frac{22}{5} } \right. \\ \\ \left \{ {y=8-3\cdot \frac{22}{5} } \atop {x= \frac{22}{5} } \right. \\ \\ \left \{ {y=8-\frac{66}{5} } \atop {x= \frac{22}{5} } \right. \\ \\ \left \{ {y=\frac{40-66}{5} } \atop {x= \frac{22}{5} } \right. [/tex]
[tex]y=- \frac{26}{5} ;x= \frac{22}{5} [/tex]
Verificare
x+2y=-6
[tex] \frac{22}{5}+2\cdot \frac{-26}{5}= \frac{22-52}{5}= \frac{-30}{5} =-6[/tex]
