Dari suatu barisan aritmatika di ketahui U4 = 8 U8 = 16 . Suku ke 12 adalah

U4 = a + 3b
8 = a + 3b ••• (1)
U8 = a + 7b
16 = a + 7b ••• (2)

a + 3b = 8
a + 7b = 16
---------------- -
-4b = -8
b = 2

a + 3b = 8
a + 3 (2) = 8
a + 6 = 8
a = 2

Maka,
U12 = a + 11b
U12 = 2 + 11 (2)
U12 = 2 + 22
U12 = 24

Mapel : matematika
Bab : Barisan dan deret

U4 = a + 3b = 8
U8 = a + 7b = 16
____________ _
-4b = -8
b = 2

a + 3b = 8
a + 3(2) = 8
a + 6 = 8
a = 2

U12 = a + 11b
U12 = 2 + 11(2)
U12 = 2 + 22
U12 = 24