Question

11．如果$\left\{\begin{array}{l}{x=1}\\{y=2}\end{array}\right.$是$\left\{\begin{array}{l}{x+2y=m}\\{3x-y=n}\end{array}\right.$的解，那么m=5，n=1．

Answer 1

分析 直接把$\left\{\begin{array}{l}x=1\\ y=2\end{array}\right.$代入方程组$\left\{\begin{array}{l}x+2y=m\\ 3x-y=n\end{array}\right.$即可得出结论．

解答 解：∵$\left\{\begin{array}{l}x=1\\ y=2\end{array}\right.$是方程组$\left\{\begin{array}{l}x+2y=m\\ 3x-y=n\end{array}\right.$的解，
∴$\left\{\begin{array}{l}1+4=m\\ 3-2=n\end{array}\right.$，即m=5，n=1．
故答案为：5，1．

点评 本题考查的是二元一次方程组的解，熟知二元一次方程组的解一定适合此方程组是解答此题的关键．