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 09-27-2012, 09:29 PM #1 Junior Member   Join Date: Sep 2012 Posts: 31 Help with SAT Math problem Just did a practice test and only missed 3(still working on math),but I can't get the hang of this problem The first term of a certain sequence is -2 and the second term is -4. Every term after the second term is obtained by dividing the sum of the previous two terms by 2. For example, the third term of the sequence is (-4)+(-2)/2= -3. What is the sixth term of this sequence? A) -3 B)-27/8 C)-21/8 D)-7/4 E)-1/8 It seemed easy but maybe I'm just confused by "... dividing the sum of the previous two terms by 2.. " Reply
 09-27-2012, 11:10 PM #2 Senior Member   Join Date: Mar 2012 Location: Cambridge, MA Posts: 1,913 a1 = -2 a2 = -4 a3 = (a1 + a2)/2 = -3 a4 = (a2 + a3)/2 = -3.5 Just carry out the calculations until you get to a6. Another way of interpreting "dividing the sum of the previous two terms by 2" is simply saying that each term is the average of the previous two terms. Reply

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