Jawabanmu

2014-05-05T13:31:15+07:00
A = 3 , b = 5-3=2 dan n = 20
Un = a + (n-1)b
U20 = 3 + (20-1)2
       = 3 + 19((2)
       = 3 + 38
       = 41

2014-05-05T13:33:43+07:00
U20 = 3,5,8,12,17,23,30,38,47,57,68,80,93,107,122,138,155,173,192,212
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