Jawabanmu

2014-05-07T14:24:24+07:00
Sn=2n^2-3n
(n/2)(a+Un) = 2n^2-3n
2a +(n-1)b = 4n-6
2a + bn - b = 4n-6
bn + (2a-b) = 4n-6
>>> bn = 4n --> b = 4
>>> 2a-b = -6 --> 2a-4 = -6 --> 2a = -2 --> a = -1
Jadi, suku pertamanya -1 dan bedanya 4