Question

Пожалуйста помогите нужны только ответы Алгебра 7 класс

Answer 1

$1)\; \; \left\{\begin{array}{l}y-2x=4\\7x-y=1\end{array}\right\; \; \left\{\begin{array}{l}y=2x+4\\7x-(2x+4)=1\end{array}\right\; \; \left\{\begin{array}{l}y=2x+4\\5x=5\end{array}\right\\\\\\\left\{\begin{array}{l}y=6\\x=1\end{array}\right\; \; \; \Rightarrow \; \; \; Otvet:\; \; (1;6)\; .$

$2)\; \; \left\{\begin{array}{l}y-2x=1\\6x-y=7\end{array}\right\; \; \left\{\begin{array}{l}y=2x+1\\6x-(2x+1)=7\end{array}\right\; \; \left\{\begin{array}{l}y=2x+1\\4x=8\end{array}\right\\\\\\\left\{\begin{array}{l}y=5\\x=2\end{array}\right\; \; \; \Rightarrow \; \; \; Otvet:\; \; (2;5)\; .$

$3)\; \; \left\{\begin{array}{l}7x-3y=13\\x-2y=5\end{array}\right\; \; \left\{\begin{array}{l}7(2y+5)-3y=13\\x=2y+5\end{array}\right\; \; \left\{\begin{array}{l}11y=-22\\x=2y+5\end{array}\right\\\\\\\left\{\begin{array}{l}y=-2\\x=1\end{array}\right\; \; \; \Rightarrow \; \; \; Otvet:\; \; (1;-2)\; .$