1. jika diketahui u5=18 dan u8=39 tentukan : a. nilai u12 2. jika diketahui u10=24 dan u15=54 tentukan : a. rumus un=.... b. u45 tolong pakai jalan yaa makasih

1. b = 39 - 18 : 8 - 5
= 21 : 3
= 7
a = U5 - (b.4)
= U5 - (7.4)
= 18 - 28
a = -10
Un = b.n (a - b)
U12 = 7.12 (-10 - 7)
= 84.-17
U12 = -336
2. a. b = 54 - 24 : 15 - 10
= 30 : 5
= 6
a = U10 - (b.9)
= 24 - (6.9)
= 24 - 54
a = -30
Un = -30 + (n-1) 6
b. U45 = -30 + (45 - 1) 6
= -30 + 44.6
= -30 + 264
U45 = 234