دانلود اپلیکیشن
دستگاه های زیر را به روش جایگزینی حل کنید.
1 \(\left\{ \begin{array}{l}x - 3y = 7\\\\2x - 7y = 15\end{array} \right.\)
2 \(\left\{ \begin{array}{l}3x - y = 6\\\\2x + \frac{1}{3}y = 8\end{array} \right.\)
1
\(\begin{array}{l}\left\{ \begin{array}{l}x - 3y = 7\\\\2x - 7y = 15\end{array} \right.\\\\x - 3y = 7 \Rightarrow x = 3y + 7\\\\2x - 7y = 15 \Rightarrow 2(3y + 7) - 7y = 15\\\\6y + 14 - 7y = 15 \Rightarrow - y = 15 - 14 = 1\\\\y = - 1\\\\x = 3( - 1) + 7 = - 3 + 7 = 4\end{array}\)
2
\(\begin{array}{l}\left\{ \begin{array}{l}3x - y = 6\\\\2x + \frac{1}{3}y = 8\end{array} \right.\\\\3x - y = 6 \Rightarrow y = 3x - 6\\\\2x + \frac{1}{3}y = 8 \Rightarrow 2x + \frac{1}{3}(3x - 6) = 8\\\\2x + x - 2 = 8 \Rightarrow 3x = 10\\\\x = \frac{{10}}{3}\\\\y = 3x - 6 = 3(\frac{{10}}{3}) - 6 = 10 - 6 = 4\end{array}\)
1736019749.png)
