用字母代表数,并让字母像数一样地参加运算,是重要的代数思想,它比算术方法先进得多,作用也大得多,这可以用下面的一个问题表明。 It is an important algebraic idea that using letters to represent numbers and letting the letters to participate in operations like numbers. It is much more advanced than the arithmetic method and has a much greater effect. This can be demonstrated by the following question.