Question

5y-x=8 |*4
5x-4y=23
плззз срочно

Answer 1

Ответ:

$\left\{\begin{array}{l}-x+5y=8\ |\cdot 5\\5x-4y=23\end{array}\right\ \oplus \ \left\{\begin{array}{l}x=5y-8\\21y=63\end{array}\right\ \ \left\{\begin{array}{l}x=15-8\\y=3\end{array}\right\ \ \left\{\begin{array}{l}x=7\\y=3\end{array}\right\\\\\\Otvet:\ \ (7;3)\ .$

Answer 2

$\displaystyle \left \{ {{5y-x=8} \atop {5x-4y=23}} \right. \to \left \{ {{-x+5y=8|*5} \atop {5x-4y=23}} \right. \to +\left \{ {{-5x+25y=40} \atop {5x-4y=23}} \right. \to 21y=63;y=63:21;y=\pmb 3 ;-x+5*3=8;-x+15=8;-x=8-15;-x=-7;x=\pmb7. Otvet:\left \{ {{x=7} \atop {y=3}} \right. \Leftrightarrow (x;y)=(7;3).$