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High school mathematics elective 2-3 cases 7 have 6 people in a row. How many arrangements do three non-adjacent people have? How to solve the exclusion method? Detailed explanation
Method 1: the exclusion method is difficult and empty. A33 (the remaining 3 people are arranged freely) times A43(3 people and 4 people, all arranged) = 144.

Method 2: The exclusion method is always * * A66, A, B and C together, and then completely arranged, A33*A44, A, B and C together, C32, and then arranged into a whole A22, which is equivalent to five, and two of them (and then a whole A22) cannot be arranged together, so the arrangement method is, A55-

It is strongly recommended not to exclude methods, which is not suitable for this topic.