Question

Решите систему уравнений 3x+5y=12
x-2y=-7 сложением

Answer 1

$\displaystyle\bf\\\left \{ {{3x+5y=12} \atop {x-2y=-7}| \ \cdot(-3)} \right. \\\\\\+\left \{ {{3x+5y=12} \atop {-3x+6y=21}} \right. \\----------\\11y=33\\\\y=3\\\\x=2y-7=2\cdot 3-7=6-7=-1\\\\Otvet:(-1 \ ; \ 3)$