tentukan suku ke delapan dari setiap barisan bilangan berikut a.1,3,6,10,... b.1,4,9,16,... c.6,12,20,30,... d.27,22,16,9,... e.1,1,2,3,5,... f.(1*2*3),(2*3*4),

a.1,3,6,10,15,21,28,36
b.1,4,9,16,25,36,49,64
c.6,12,20,30,42,56,72,90
d.27,22,16,9,1,-8,-18,-29
e.1,1,2,3,5,8,13,21
f.(1*2*3),(2*3*4),(3*4*5),(4*5*6),(5*6*7),(6*7*8),(7*8*9),(8*9*10)