Question

Как решить систему способом подстановки 5x+y=7; 7x-4y=-1

Answer 1

Ответ:

$\left\{\begin{array}{l}5x+y=7\\7x-4y=-1\end{array}\right\ \ \left\{\begin{array}{l}y=7-5x\\7x-4(7-5x)=-1\end{array}\right\ \ \left\{\begin{array}{l}y=7-5x\\7x-28+20x=-1\end{array}\right\\\\\\\left\{\begin{array}{l}y=7-5x\\27x=27\end{array}\right\ \ \left\{\begin{array}{l}y=7-5\\x=1\end{array}\right\ \ \left\{\begin{array}{l}y=2\\x=1\end{array}\right\ \ \ Otvet:\ (1;2)\ .$