Question

16．下列二元一次方程组的解为$\left\{\begin{array}{l}{x=1}\\{y=-1}\end{array}\right.$的是（　　）

• A． $\left\{\begin{array}{l}{x+y=0}\\{x-y=1}\end{array}\right.$
• B． $\left\{\begin{array}{l}{x+y=0}\\{x-y=-1}\end{array}\right.$
• C． $\left\{\begin{array}{l}{x+y=0}\\{x-y=2}\end{array}\right.$
• D． $\left\{\begin{array}{l}{x+y=0}\\{x-y=-2}\end{array}\right.$

Answer 1

分析 根据方程组的解的定义把$\left\{\begin{array}{l}{x=1}\\{y=-1}\end{array}\right.$分别代入各个方程组进行验证，选出满足的一项即可．

解答 解：$\left\{\begin{array}{l}{x=1}\\{y=-1}\end{array}\right.$不满足A，A不正确；
$\left\{\begin{array}{l}{x=1}\\{y=-1}\end{array}\right.$不满足B，B不正确；
$\left\{\begin{array}{l}{x=1}\\{y=-1}\end{array}\right.$满足C，C正确；
$\left\{\begin{array}{l}{x=1}\\{y=-1}\end{array}\right.$不满足D，D不正确，
故选：C．

点评 本题考查的是二元一次方程组的解的判断，掌握二元一次方程组的定义是解题的关键，注意要正确计算才能选出正确的答案．