Question

20．方程組$\left\{\begin{array}{l}4x-3y=k\\ 2x+3y=5\end{array}\right.$的解與x與y的值相等，則k等于（　�。�

• A． 1
• B． 2
• C． 3
• D． 4

Answer 1

分析 將y=x代入方程組$\left\{\begin{array}{l}4x-3y=k\\ 2x+3y=5\end{array}\right.$，得$\left\{\begin{array}{l}{x=k}\\{5x=5}\end{array}\right.$，解此方程組即可求出k的值．

解答 解：將y=x代入方程組$\left\{\begin{array}{l}4x-3y=k\\ 2x+3y=5\end{array}\right.$，得$\left\{\begin{array}{l}{x=k}\\{5x=5}\end{array}\right.$，
解得：$\left\{\begin{array}{l}{x=1}\\{k=1}\end{array}\right.$，
故選：A．

點評 本題考查的是解二元一次方程組，解決本題的關鍵是解二元一次方程組．