Răspuns:
1.
[tex]\left \{ {{3x-\frac{y}{2} +x=0} \atop {2x-\frac{y}{3}+y=4 }} \right. = \left \{ {{8x-y=0} \atop {6x+2y=12}} \right. =\left \{ {{8x-y=0} \atop {3x+y=6}} \right.[/tex]
-daca adunam cele doua ecuatii se reduce o variabila, adica y;
[tex]8x-y+3x+y=0+6\\11x=6\\x=\frac{6}{11}\\\\8\frac{6}{11} -y=0\\y=\frac{48}{11} \\[/tex]
3.
[tex]\left \{ {{\frac{2}{5}x+5y=-\frac{2}{5} } \atop {\frac{1}{3}x-\frac{5}{12}y=-\frac{1}{3} }} \right. =\left \{ {{2x+25y=-2/(-2)} \atop {4x-5y=-4}} \right. =\left \{ {{-4x-50y=4} \atop {4x-5y=-4}} \right. \\\\-55y=0\\y=0\\\\4x-0=-4\\x=-1[/tex]
