第三章整式的加减由数到式的学习是从具体的数字到抽象的字母的学习过程。有理数中有整数和分数,可联想到式中也会有整式和分式的学习;数有各种运算,当然式也应当研究它的运算,这就是学习中要具备的联想和类比的数学思想。整式是式中最简单又是最基础的知识,应当学好。 The addition and subtraction of the third chapter of the whole formula by number-to-style learning is a learning process from concrete numbers to abstract letters. There are integers and scores in rational numbers. It can be concluded that there are also integer and fractional learnings in the formula; there are various kinds of calculations in the numbers, and of course, the calculations in the formulas should also be studied. This is the mathematical thinking of association and analogy in learning. . The whole formula is the simplest and most basic knowledge in the formula and should be learned well.