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第1点分类加法计数原理与分步乘法计数原理(★★★★)必做1一个小朋友有5支不同颜色的水彩笔,老师要求用这5支笔给图中的四个区域涂色,规定一个区域只涂一种颜色,相邻的区域颜色不同,那么小朋友有______种不同的涂色方案.图1牛刀小试精妙解法先分为两类:第一类,当D与A不同色,则可分为四步完成.第一步,涂A有5种方法;第二步,涂D有4种方法;第三步,涂C有3种方法;第四步,涂B有3种方法.由分步乘法计数原理,共有5×4×3×3=180种方法.第二类,当D与A同色,分三步完
The first point classification plus counting principle and the step-by-step multiplication counting principle (1) a child must have 5 different colors of watercolor pen, the teacher asked to use these five pens to paint the four regions in the picture, Provisions of a region only painted a color, adjacent to different colors, then children have ______ different kinds of coloring scheme .Figure 1 chopper small test subtle solution First divided into two categories: The first category, when D and A different colors , Can be divided into four steps to complete the first step, there are five ways to paint A; the second step, there are four ways to paint D; the third step, there are three ways to paint C; A total of 5 × 4 × 3 × 3 = 180 kinds of methods. The second category, when D and A the same color, in three steps End