初学二元一次方程(组)时,同学们由于对概念理解不清,对方程组的解法理解不够透彻或在解题时忽略某些条件等,常会出现这样或那样的错误.一、忽视“未知数的系数不为零”这一隐含条件出错例1若(a-3)x+y~(|a|-2)=9是关于x,y的二元一次方程,则a的值是____.错解:由二元一次方程的定义得|a|-2=1,解得a=±3.剖析:在二元一次方程必须满足的条件中,“二元”指方程中必须含有两个未知 Beginner binary equation (group), the students due to unclear understanding of the concept, solution to the equation group is not thorough enough or ignore some conditions in the problem-solving, etc., often appear this or that mistake.One, ignore “The coefficient of the unknowns is not zero ” This implied condition is wrong Example 1 If (a-3) x + y ~ (| a | -2) = 9 is a bivariate equation about x, y, The value is ____. The wrong solution: the definition of a bivariate equation was | a | -2 = 1, solution a = ± 3. Analysis: In the condition of the binary equation must be met, “binary” Refers to the equation must contain two unknown