例题当a为何值时,方程组{3x-5y=2a 2x+7y=a-18的解x,y互为相反数?一、问题回顾这类问题是学习《二元一次方程组》这一章节内容时经常会碰到的一类问题,也是大部分学生在解决的过程中会出现困惑的一类问题.从知识层面看:这个方程组含有x,y,a三个字母,有别于常见的含两个字母的二元一次方程组,大大增加了题目本身的难度;从解决问题的层面看:对于含有三个字母的方程组而 Example When a is the value of the system of equations {3x-5y = 2a 2x + 7y = a-18 solution x, y each other the opposite number? A review of the problem This type of problem is to learn the "binary system of equations Chapter content often encounter a class of problems, but also most students in the process of solving a confusion of a class of problems.From the knowledge level: This equation contains x, y, a three letters, there are In the common two-letter binary system of equations, which greatly increased the difficulty of the title itself; from the problem-solving level to see: For a three-letter system of equations