一、正确理解同类项所含字母相同,并且相同字母的指数也相同的项叫同类项,几个常数项也是同类项.关于同类项的概念应注意以下三点:(1)判断多项式的项是不是同类项就看两条:①所含字母相同;②相同字母的指数也相同,二者缺一不可.(2)同类项与系数无关,与字母的排列顺序也无关.(3) First, the correct understanding of the same type of letters contained in the same letter, and the same letter index is also called the same type of items, several constant items are similar items. About the concept of similar items should pay attention to the following three points: (1) determine the polynomial items Is not the same category to see two: 1 contains the same letter; 2 the same letter of the index is also the same, both are indispensable. (2) The same type of factor has nothing to do with the order of the letter is also irrelevant. (3)