1. 1. Решение. Начальные преобразования (общие для обоих методов).<span><span>{<span><span>2<span>(x+y)</span>−x=−6</span><span>3x−<span>(x−y)</span>=0</span></span></span>⇒</span><span>{<span><span>2y+x=−6</span><span>2x+y=0</span></span></span>Решение методом подстановки.<span><span>{<span><span>x+2y=−6</span><span>2x+y=0</span></span></span>⇒</span><span><span>{<span><span>x=−2y−6</span><span>2x+y=0</span></span></span>⇒</span><span><span>{<span><span>x=−2y−6</span><span>2<span>(−2y−6)</span>+y=0</span></span></span>⇒</span><span><span>{<span><span>x=−2y−6</span><span>−3y−12=0</span></span></span>⇒</span><span><span>{<span><span>x=−2y−6</span><span>y=−4</span></span></span>⇒</span><span>{<span><span>x=2</span><span>y=−4</span></span></span>Ответ:<span><span>(2;−4)</span></span>