Question

алгебра помогите пожалуйста ​

Answer 1

$\displaystyle\bf\\1)\\\\\left \{ {{y=x+2} \atop {x+y=8}} \right. \\\\\\+\left \{ {{-x+y=2} \atop {x+y=8}} \right. \\--------\\2y=10\\\\y=5\\\\x=8-y=8-5=3\\\\Otvet \ : \ (3 \ ; \ 5)\\\\\\2)\\\\\left \{ {{x+2y=3} \ |\cdot(-1) \atop {x+3y=8}} \right. \\\\\\+\left \{ {{-x-2y=-3} \atop {x+3y=8}} \right.\\ ---------\\y=5\\\\x=3-2y=3-2\cdot 5=3-10=-7\\\\Otvet \ : \ (-7 \ ; \ 5)\\\\\\3)\\\\\left \{ {{x+3y=1} \ |\cdot(-1) \atop {x-4y=15}} \right.$

$\displaystyle\bf\\+\left \{ {{-x-3y=-1} \atop {x-4y=15}} \right. \\----------\\-7y=14\\\\y=14:(-7)=-2\\\\x=1-3y=1-3\cdot(-2)=1+6=7\\\\Otvet \ : \ (7 \ ; \ -2)$