Question

U1 = 4, u2 = 6, u3 = 10, u4 = 16, u5 = 24. suku ke 20 adalah...
a. 422
b. 412
c. 384
d. 363

Answer 1

Verified answer

Kelas 8 Matematika
Bab Barisan dan Deret Bilangan

4, 6, 10, 16, 24, .... → a = 4
  2, 4,  6,  8, ..    → b = 2
    2, 2,  2,      → c = 2
n = 20

Un = a + (n - 1) . b + 1/2 . (n - 1) . (n - 2) . c
U20 = 4 + 19 . 2 + 1/2 . 19 . 18 . 2
U20 = 4 + 38 + 342
U20 = 384