Question

Допоможіть, будь ласка, заздалегідь дякую)​

Answer 1

$\displaystyle\bf\\1)\\\\+\left \{ {{x-y=5} \atop {2x+y=1}} \right. \\--------\\3x=6\\\\x=6:3=2\\\\y=x-5=2-5=-3\\\\Otvet \ : \ (2 \ ; \ -3)\\\\2)\\\\+\left \{ {{x+y=5} \atop {x-y=1}} \right. \\--------\\2x=6\\\\x=6:2=3\\\\y=5-x=5-3=2\\\\Otvet \ : \ (3 \ ; \ 2)\\\\3)\\\\\left \{ {{2x+y=6} \ |\cdot 3 \atop {4x-3y=2}} \right. \\\\\\+\left \{ {{6x+3y=18} \atop {4x-3y=2}} \right. \\---------\\10x=20\\\\x=20:10=2\\\\y=6-2x=6-2\cdot2=6-4=2\\\\Otvet \ : \ (2 \ ; \ 2)$

$\displaystyle\bf\\4)\\\\\left \{ {{3x+2y=5} \ |\cdot 3\atop {5x-3y=2} \ |\cdot2} \right. \\\\\\+\left \{ {{9x+6y=15} \atop {10x-6y=4}} \right. \\---------\\19x=19\\\\x=19:19=1\\\\2y=5-3x=5-3\cdot 1=5-3=2\\\\y=2:2=1\\\\Otvet \ : \ (1 \ ; \ 1)$