Question

системы
1) решить методом подстановки
8x - 5y = -53
8x + y = -47

2) Решите систему уравнений методом сложения:
−9x−7y=59
x+7y=−19​

Answer 1

$1)\left \{\begin{array}{l}8x-5y=-53} \\ {8x+y=-47}}\end{array} \right. \\\\\\\left \{\begin{array}{l}8x-5y=-53} \\ {y=-8x-47}}\end{array} \right.\\\\\\\left \{\begin{array}{l}8x-5(-8x-47)=-53} \\ {y=-8x-47}}\end{array} \right.\\\\\\\left \{\begin{array}{l}8x+40x+235=-53} \\ {y=-8x-47}}\end{array} \right.\\\\\\\left \{\begin{array}{l}48x=-288} \\ {y=-8x-47}}\end{array} \right.\\\\\\\left \{\begin{array}{l}x=-6} \\ {y=-8\cdot(-6)-47}}\end{array} \right.$

$\left \{\begin{array}{l}x=-6} \\ {y=1}}\end{array} \right.\\\\Otvet:\boxed{(-6 \ ; \ 1)}\\\\\\2)\\+\left \{\begin{array}{l}-9x-7y=59} \\ {x+7y=-19}}\end{array} \right.\\----------\\-8x=40\\\\x=40:(-8)=-5\\\\7y=-x-19=-(-5)-19=5-19=-14\\\\y=-14:7=-2\\\\Otvet:\boxed{(-5 \ ; \ -2)}$