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同学们初学代数,刚接触到变量还有些不适应.比如,长为 a、宽为 b 的长方形面积可用含变量 a、b 的代数式表示为S=ab.有些同学可能会纳闷:“那么,长方形的面积究竟是多少?”问得好!的确,ab 是一个代数式,并没有告诉我们长方形面积的具体数值.但它给出了计算长为 a、宽为 b 的任意长方形的面积的方法,即可由 a 和b 的乘积得到.可以说,公式 S=ab 只是一个算法表达式,告诉我们怎样算,而不是具体地算出结果.也就是说,一旦长 a、宽 b 是已知的(例如 a=3,b=
Students begin to learn algebra, but some new ones are not adapted to the variables. For example, a rectangle with length a and width b can be expressed as algebraic expressions with variables a and b as S=ab. Some students may wonder: “Then, rectangles What is the size of the area?” Well! Indeed, ab is algebraic and does not tell us about the specific value of the area of the rectangle. But it gives a way to calculate the area of an arbitrary rectangle of length a and width b, ie It can be obtained by the product of a and b. It can be said that the formula S=ab is just an algorithm expression that tells us how to calculate, rather than specifically calculating the result. That is, once the length a and the width b are known (for example, a =3,b=