tentukan beda suku ke-n tiap barisan aritmatika . a. 1/3 ,8/15 ,11/15,14/15

jawab

1/3, 8/15, 11/15,14/15

= 5/15, 8/15, 11/15, 14/15
a= 1/3
b = 8/15 - 5/15 = 3/15 = 1/5


un = a + (n-1)b
un = 1/3  + (n-1)(1/5)
un = 1/3 + 1/5 n - 1/5
un = 1/15 ( 5 + 3n - 3)
un = 1/15 (3n + 2)