Question

12．若方程组$\left\{\begin{array}{l}bx-2y=2\\ ax+3y=5\end{array}\right.$的解是$\left\{\begin{array}{l}x=2\\ y=1\end{array}\right.$，则a、b的值为（　　）

• A． $\left\{\begin{array}{l}a=3\\ b=-2\end{array}\right.$
• B． $\left\{\begin{array}{l}a=-1\\ b=3\end{array}\right.$
• C． $\left\{\begin{array}{l}a=0\\ b=2\end{array}\right.$
• D． $\left\{\begin{array}{l}a=1\\ b=2\end{array}\right.$

Answer 1

分析 把x与y的值代入方程组求出a与b的值即可．

解答 解：把$\left\{\begin{array}{l}{x=2}\\{y=1}\end{array}\right.$代入方程组得：$\left\{\begin{array}{l}{2b-2=2}\\{2a+3=5}\end{array}\right.$，
解得：$\left\{\begin{array}{l}{a=1}\\{b=2}\end{array}\right.$，
故选D

点评 此题考查了二元一次方程组的解，方程组的解即为能使方程组中两方程成立的未知数的值．