Question

Решите систему уравнений
{ 7х+3у=17
{ -2(х+3)+5у=-5

Answer 1

$\displaystyle\bf\\\left \{ {{7x+3y=17} \atop {-2(x+3)+5y=-5}} \right. \\\\\\\left \{ {{7x+3y=17} \atop {-2x-6+5y=-5}} \right. \\\\\\\left \{ {{7x+3y=17} \ |\cdot 2 \atop {-2x+5y=1 \ |\cdot 7}} \right. \\\\\\+\left \{ {{14x+6y=34} \atop {-14x+35y=7 }} \right. \\-----------\\41y=41\\\\y=1\\\\2x=5y-1=5\cdot 1-1=5-1=4\\\\x=4:2=2\\\\\\Otvet \ : \ (2 \ ; \ 1)$