Question

11．方程x+3y=-8的负整数解有2组，分别是$\left\{\begin{array}{l}{x=-5}\\{y=-1}\end{array}\right.$，$\left\{\begin{array}{l}{x=-2}\\{y=-2}\end{array}\right.$．

Answer 1

分析 把y看做已知数表示出x，即可确定出负整数解．

解答 解：方程x+3y=-8，
解得：x=-3y-8，
当y=-1时，x=-5；y=-2时，x=-2；
则方程的负整数解有2组，分别为$\left\{\begin{array}{l}{x=-5}\\{y=-1}\end{array}\right.$，$\left\{\begin{array}{l}{x=-2}\\{y=-2}\end{array}\right.$．
故答案为：2；$\left\{\begin{array}{l}{x=-5}\\{y=-1}\end{array}\right.$，$\left\{\begin{array}{l}{x=-2}\\{y=-2}\end{array}\right.$．

点评 此题考查了解二元一次方程，解题的关键是将y看做已知数求出x．