Question

12．若方程組$\left\{\begin{array}{l}bx-2y=2\\ ax+3y=5\end{array}\right.$的解是$\left\{\begin{array}{l}x=2\\ y=1\end{array}\right.$，則a、b的值為（　�。�

• 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與y的值代入方程組求出a與b的值即可．

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

點(diǎn)評 此題考查了二元一次方程組的解，方程組的解即為能使方程組中兩方程成立的未知數(shù)的值．