Dua suku berikutnya dari barisan bilangan: 51,48,45,42,...,..., adalah...

51, 48, 45, 42, ..., ...

Bedanya sama, yaitu 3
maka 2 suku berikutnya:
(42 - 3), (42 - 3 × 2)
= 39, 36

b = -3
a = 51
Un = a + (n-1)× b
U5 = 51 + (5 - 1) ×(-3)
= 51 + (4×(-3))
= 51 - 12
= 39
U6 = 51 + (6 - 1 ) × ( -3)
= 51 + (5×(-3)
= 51 - 15
= 36
U7 = 51 + (7 - 1) × (-3)
= 51 + (6×(-3)
= 51 - 18
= 33