Question

Rezolvati sistemul de ecuatii: acolada si sus 3x+y=-2 iar jos -5x-3y=2.

Answer 1

y=-2-3x            ⇔y=-2-3x    ⇔y=-2-3x    ⇔        y=-2-3x⇔y=-2+3⇔y=1
-5x-3(-2-3x)=2      -5+6+9x=2     4x=4                    x=-1        x=-1      x=-1  

Answer 2

$\left \{ {{3x+y=-2} \atop {-5x-3y=2}} \right. =\ \textgreater \ \left \{ {{y=-2-3x} \atop {-5x-3(-2-3x)=2}} \right. =\ \textgreater \ \left \{ {{y=-2-3x} \atop {-5x+6+9x=2}} \right. =\ \textgreater \ \left \{ {{y=-2-3x} \atop {4x=-4}} \right. =\ \textgreater \ \\ \left \{ {{y=-2-3*(-1)} \atop {x=-1}} \right. =\ \textgreater \ \left \{ {{y=1} \atop {x=-1}} \right.$
$S={-1, 1}$