Question

Решить систему методом подстановки х+4у=-6 3х-у=8 решите методом сложения систему уравнения 7х+3у=43 4х-3у=67

Answer 1

$1.\\\\\left \{\begin{array}{lcl} {{x+4y=-6} \\ {3x-y=8}}\end{array} \right. \\\\\\ \left \{\begin{array}{lcl} {{x+4(3x-8)=-6} \\ {y=3x-8}}\end{array} \right. \\\\\\\left \{\begin{array}{lcl} {{x+12x-32=-6} \\ {y=3x-8}}\end{array} \right.\\\\\\\left \{\begin{array}{lcl} {{13x=26} \\ {y=3x-8}}\end{array} \right.\\\\\\\left \{\begin{array}{lcl} {{x=2} \\ {y=-2}}\end{array} \right.$

$2.\\\\+\left \{\begin{array}{lcl} {{7x+3y=43} \\ {4x-3y=67}}\end{array} \right. \\\\\\\left \{\begin{array}{lcl} {{11x=110} \\ {4x-3y=67}}\end{array} \right. \\\\\\\left \{\begin{array}{lcl} {{x=10} \\ {40-3y=67}}\end{array} \right.\\\\\\\left \{\begin{array}{lcl} {{x=10} \\ {y = -9}}\end{array} \right.$