Question

18．已知方程組$\left\{\begin{array}{l}{2x-5y=-21}\\{4x+3y=23}\end{array}\right.$的解為$\left\{\begin{array}{l}{x=2}\\{y=5}\end{array}\right.$，則方程組$\left\{\begin{array}{l}{2（x-1）-5（y+3）=-21}\\{4（x-1）+3（y+3）=23}\end{array}\right.$的解為（　　）

• A． $\left\{\begin{array}{l}{x=2}\\{y=5}\end{array}\right.$
• B． $\left\{\begin{array}{l}{x=1}\\{y=8}\end{array}\right.$
• C． $\left\{\begin{array}{l}{x=-3}\\{y=-2}\end{array}\right.$
• D． $\left\{\begin{array}{l}{x=3}\\{y=2}\end{array}\right.$

Answer 1

分析 仿照已知方程組的解確定出所求方程組的解即可．

解答 解：∵方程組$\left\{\begin{array}{l}{2x-5y=-21}\\{4x+3y=23}\end{array}\right.$的解為$\left\{\begin{array}{l}{x=2}\\{y=5}\end{array}\right.$，
∴方程組$\left\{\begin{array}{l}{2（x-1）-5（y+3）=-21}\\{4（x-1）+3（y+3）=23}\end{array}\right.$的解為$\left\{\begin{array}{l}{x-1=2}\\{y+3=5}\end{array}\right.$，
解得：$\left\{\begin{array}{l}{x=3}\\{y=2}\end{array}\right.$，
故選D

點(diǎn)評(píng) 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都成立的未知數(shù)的值．