Question

1．二元一次方程2x+y=5的正整数解为$\left\{\begin{array}{l}{x=1}\\{y=3}\end{array}\right.$，$\left\{\begin{array}{l}{x=2}\\{y=1}\end{array}\right.$．

Answer 1

分析 将x看做已知数求出y，即可确定出正整数解．

解答 解：方程2x+y=5，
解得：y=-2x+5，
当x=1时，y=3；x=2时，y=1，
则方程的正整数解为$\left\{\begin{array}{l}{x=1}\\{y=3}\end{array}\right.$，$\left\{\begin{array}{l}{x=2}\\{y=1}\end{array}\right.$，
故答案为：$\left\{\begin{array}{l}{x=1}\\{y=3}\end{array}\right.$，$\left\{\begin{array}{l}{x=2}\\{y=1}\end{array}\right.$

点评 此题考查了解二元一次方程，熟练掌握运算法则是解本题的关键．