In a arithmetic sequence t1,t2,t3,....tn,...,t1=23 and tn=tn-1-3 for each n>1,
what is the value of n when tn=-4?
(A)-1 (B)7 (C)10 (D)14 (E)20
The answer is (C) ,but why?
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04/24 21:26, , 1F
04/24 21:26, 1F
→
04/24 22:21, , 2F
04/24 22:21, 2F
推
04/24 22:40, , 3F
04/24 22:40, 3F
→
04/24 22:41, , 4F
04/24 22:41, 4F