suku ke 10 barisan 15,24,35.48

Bab Barisan dan Deret
Matematika SMP Kelas IX

15, 24, 35, 48, .... → a = 15
....9.....11.....13.... → b = 9
........2.....2..... → c = 2

Un = a + (n - 1) b + 1/2 x (n - 1) x (n - 2) x c
U10 = 15 + (9 x 9) + (1/2 x 9 x 8 x 2)
U10 = 15 + 81 + 72
U10 = 168