suku ke 50 barisan bilangan 3,8,15,24,35...adalah

jawab

3...8...15...24...35
..+5.+7..+9
.....+2..+2

a= 3
b = 5
c= 2
n = 50
un = a+(n-1)b + c/2 (n-1)(n-2)

u50 = 3 + 49(5) + 2/2 (49)(48)
u50 = 3 +245 +2.352
u50 = 2.600