[tex]\displaystyle\bf\\1)\\\\\left \{ {{x+y=4} \atop {3x+y=6}} \right. \\\\\\\left \{ {{y=4-x} \atop {3x+4-x=6}} \right.\\\\\\\left \{ {{y=4-x} \atop {2x=6-4}} \right. \\\\\\\left \{ {{y=4-x} \atop {2x=2}} \right. \\\\\\\left \{ {{y=4-1} \atop {x=1}} \right.\\\\\\\left \{ {{y=3} \atop {x=1}} \right. \\\\\\Otvet \ : \ (1 \ ; \ 3)[/tex]

[tex]\displaystyle\bf\\2)\\\\\left \{ {{x-y=0} \atop {x-2y=8}} \right. \\\\\\\left \{ {{x=y} \atop {y-2y=8}} \right. \\\\\\\left \{ {{x=y} \atop {-y=8}} \right. \\\\\\\left \{ {{x=-8} \atop {y=-8}} \right. \\\\\\Otvet \ : \ (-8 \ ; \ -8)[/tex]