{5Х-2У=19 {7Х-4У=17 РЕШИТЬ УРАВНЕНИЕ СПОСОБОМ ПОДСТАНОВКИ

[latex] \left \{ {5x-2y=19;|:2} \atop {7x-4y=17;}} \right. \ \textless \ =\ \textgreater \ \left \{ {{2,5x-y=9,5;} \atop {7x-4y=17;}} \right. \ \textless \ =\ \textgreater \ \left \{ {{-y=9,5-2,5x;} \atop {7x-4y=17;}} \right. \ \textless \ =\ \textgreater \ \\ \ \textless \ =\ \textgreater \ \left \{ {{{y=2,5x-9,5;} \atop {7x-4({2,5x-9,5)=17;}} \right. \ \textless \ =\ \textgreater \ \left \{ {{{y=2,5x-9,5;} \atop {7x-10x+38-17=0;}} \right. \ \textless \ =\ \textgreater \ \\ \ \textless \ =\ \textgreater \ \left \{ {{{y=2,5x-9,5;} \atop {-3x=-21;}} \right. \ \textless \ =\ \textgreater \ \left \{ {{x=7;} \atop {5*7-2y=19;}} \right. \ \textless \ =\ \textgreater \ \left \{ {{x=7;} \atop {y=8.}} \right. [/latex] Ответ: [latex](7;8)[/latex].