suku ke 4 =65 dan suku ke 8=125.hitung suku ke 10

U4 = 65
a + 3b = 65
a = 65 - 3b

U8 = 125
a + 7b = 125
65 - 3b + 7b = 125
4b = 60
b = 60/4
b = 15

a = 65 - 3b
a = 65 - 3(15)
a = 65 - 45
a = 20

suku ke sepuluh
U10
= a + 9b
= 20 + 9(15)
= 20 + 135
= 155

U4 = a+3b = 65
U8 = a+7b = 125
---------------------- -
-4b = -60
b = 15

subtitusi :
a+3b = 65
a + 3(15) = 65
a + 45 = 65
a = 65-45
a = 20

maka suku ke-10
U10 = a + 9b
U10 = 20 + 9(15)
U10 = 20 + 135
U10 = 155