Tuliskan aturan pembentukan setiap barisan berikut ini! A.7,8,11,13..... B.1,4,9,16.... C.2,6,12,20... D.99,87,75,63

jawab

b. 1, 4, 9, 16 --> 1², 2², 3², 4²
un  = n²

c. 2, 6, 12, 20 --> 
2 = 1(1+1)
6 = 2 (2+1)
12 = 3(3+1)
20 = 4 (4 +1)
Un = n (n+1)

d. 99, 87, 75, 63
99  = 111- 12(1)
87 = 111- 12(2)
75 = 111- 12(3)
63 = 111 - 12(4)
un = 111 - 12n