Question

16．二元一次方程組$\left\{\begin{array}{l}x+y=5\\ 2x+y=8\end{array}\right.$的解是（　　）

• A． $\left\{\begin{array}{l}x=2\\ y=3\end{array}\right.$
• B． $\left\{\begin{array}{l}x=1\\ y=4\end{array}\right.$
• C． $\left\{\begin{array}{l}x=3\\ y=2\end{array}\right.$
• D． $\left\{\begin{array}{l}x=4\\ y=1\end{array}\right.$

Answer 1

分析 方程組利用加減消元法求出解即可．

解答 解：$\left\{\begin{array}{l}{x+y=5①}\\{2x+y=8②}\end{array}\right.$，
②-①得：x=3，
把x=3代入①得：y=2，
則方程組的解為$\left\{\begin{array}{l}{x=3}\\{y=2}\end{array}\right.$，
故選C

點(diǎn)評(píng) 此題考查了解二元一次方程組，利用了消元的思想，消元的方法有：代入消元法與加減消元法．