Jawabanmu

2014-02-27T18:40:22+07:00
Suku awal = 3, beda = 3, dan Un = 75
Un = a + (n-1)b
75 = 3 + (n-1) 3
72 = (n-1)3
72/3= (n-1)
24 = n-1
n= 25
1 2 1