题目
(6分) 如图①、图②、图③……是用围棋子摆成的一列具有一定规律的“山”字.(1) 按图示的规律填空. 图形标号 ① ② ③ ④ …… 围棋子的数目(颗) 7 (2) 第n个图形所对应的围棋子的数目为___________颗.若某个图形中有围棋子142颗,它是第__________个图形.
答案: (1) 12,17,22 (2) (3) 28 解析:解:(1) 12,17,22···················································································· 3分(2) ·················································································· 5分(3) 28·························································································· 6分