suatu barisan aritmatika3,6,9... suku ke 10 barisan tersebut adalah

a = 3
b = 3
U10 = a +9b
U10 = 3 + 9(3) = 3 + 27 = 30

U10= a + (n-1) × b
= 3 + (10-1) × 3
= 3 + 9 × 3
= 3 + 27
U10 = 30