Question

Номер 672 (1), решить методом сложения

Answer 1

Ответ:

$\left \{ {{2(x+y)-3(x-y)=4} \atop {5(x+y)-7(x-y)=2}} \right. =\left \{ {{2x+2y-3x+3y=4} \atop {5x+5y-7x+7y=2}} \right. =\left \{ {{-x+5y=4 } \atop {-2x+12y=2}} \right.= \left \{ {{2x+10y=8} \atop {-2x+12y=2}} \right. =\\24y=10 \\y=2,4\\\\\\-x+5*2,4=4\\-x=4-12\\-x=-8\\x=8$