Question

Suku ke 8 dan ke 20 baris aritmatik adalah 23 dan 59. maka suku ke 10 adalah?

Answer 1

U8 = 23
a+7b = 23
a = 23-7b

u20 = 59
a+19b = 59
23-7b+19b = 59
12b = 59-23
12b = 36
b = 3
a = 23-7b
a = 23-7(3)
a = 23-21
a = 2

u10 = a+9b
u10 = 2+9(3)
u10 = 2+27
u10 = 29