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一.必备知识 1.回答下面各问题。(1)比例的意义是什么?(2)比例的基本性质如何叙述?(3)比例尺的意义怎么表示?(4)解比例的根据是什么?(5)正反比例的意义怎样描述?(6)正反比例的数学表达式是什么? 2.判断正误。(1)在比例里,如果两个外项互为倒数,则两个内项的积一定是1。(2)如果XY=1,则X与Y成反比例。(3)一般地,把比例尺写成前项是1的比,但有时也把比例尺写成后项是1的比。 3.解比例。(1)2:8=X:4 (2)3:1.2=x/6 4.小花用1:100的比例尺把自己卧室的占地面积(长方形)画在了一
I. Essential knowledge 1. Answer the following questions. (1) What is the significance of the ratio? (2) How to describe the basic nature of the ratio? (3) How to represent the meaning of the scale? (4) What is the basis of the proportional scale? (5) ) What is the mathematical expression of positive and negative proportion? 2. Judgment correct. (1) In proportions, the product of two interior terms must be 1 if both terms are reciprocal. (2) If XY = 1, then X is inversely proportional to Y. (3) In general, the scale is written as the ratio of the preceding term is 1, but sometimes the scale is written as the ratio of the latter term is 1. 3. Solution ratio. (1) 2: 8 = X: 4 (2) 3: 1.2 = x / 6 4. Florets draw their own bedroom area (rectangle) on a 1: 100 scale