Question

Пж даю 40 бл.Пж помогите пожалуйста решить....

Answer 1

$1)\left \{ {{5(x-2)+7=9+4x} \atop {4(x-y)-5y=39}} \right.\\\\\left \{ {{5x-10+7=9+4x} \atop {4x-4y-5y=39}} \right.\\\\\left \{ {{5x-4x=9+3} \atop {4x-9y=39}} \right. \\\\\left \{ {{x=12} \atop {9y=4x-39}} \right.\\\\\left \{ {{x=12} \atop {9y=4*12-39}} \right.\\\\\left \{ {{x=12} \atop {9y=9}} \right. \\\\\left \{ {{x=12} \atop {y=1}} \right.\\\\Otvet:\boxed{(12 \ ; \ 1)}$

$2)\left \{ {{\frac{1}{3}(x-y)=4 } \atop {\frac{1}{4}(x+y)=2 }} \right. \\\\\left \{ {{\frac{1}{3}(x-y)=4|*3 } \atop {\frac{1}{4}(x+y)=2 }|*4} \right.\\\\+\left \{ {{x-y=12} \atop {x+y=8}} \right.\\------\\ 2x=20\\\\x=10\\\\y=8-x=8-10=-2\\\\Otvet:\boxed{(10 \ ; \ -2)}$