Tolong di bantu,pakai caranya Tentukan suku ke-120 Dari A.10,8,6.... B.1/2,1,3/2....

a.)
dik :
a = 10
b = 8 - 10 = -2

Dit :
U120 ?

jawab :
Un = a + (n-1) b
U120 = 10 + (120-1) (-2)
U120 = 10 + 119 . (-2)
U120 = -228

b)
dik :
a = 1/2
b = 1 - 1/2 = 1/2

dit :
U120 ?

jawab :
Un = a + (n-1) b
U120 = 1/2 + (120-1) 1/2
U120 = 1/2 + 119 . 1/2
U120 = 60