Question

Diketahui barisan bilangan 12, 20, 30, 42, 56,....
Suku ke-22 adalah..



tolong bantu pake cara ya kak makasihh​

Answer 1

12 = 12

20 = 12 + 8

30 = 12 + 8 + 10

42 = 12 + 8 + 10 + 12

56 = 12 + 8 + 10 + 12 + 14=> a = 8, b = 2

U22 = 12 + Sn=> n = 21

= 12 + n/2 (2a + (n - 1)b)

= 12 + 21/2 (2.8 + 20(2))

= 12 + 21/2 (16 + 40)

= 12 + 21/2 (56)

= 12 + 21 (28)

= 12 + 588

= 600

Semoga membantu:)