(1) 1,7,8,57,121 (2)7,9,-1,5,-3 (3)4,2,2,3,6,15

(1) 1,7,8,57,121规律：1^2＋7＝8,7^2＋8＝57,8^2＋57＝121(2)7,9,-1,5,-3 规律：(7－9)÷2＝-1,(9－(-1))÷2＝5,(-1－5)÷2＝-3(3)4,2,2,3,6,15规律：4×0.5＝2,2×1＝2,2×1.5＝3,3×2＝6,6×2.5＝15...