Question 252888: 1, 2, 1, –1, –2, . . .
The first five terms of a sequence are shown above. After the second term, each term can be obtained by subtracting from the previous term the term before that. For example, the third term can be obtained by subtracting the first term
from the second term. What is the sum of the first 36 terms of the sequence ?
(A) 0 (B) 4 (C) 12 (D) 24 (E) 30
Answer by drk(1908)   (Show Source):
You can put this solution on YOUR website! Here is the question:
1, 2, 1, –1, –2, . . .
The first five terms of a sequence are shown above. After the second term, each term can be obtained by subtracting from the previous term the term before that. For example, the third term can be obtained by subtracting the first term
from the second term.
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step 1: continue the pattern:
1, 2, 1, -1, -2, -1, 1, 2, . . .
Notice that it starts all over after 6 terms. THat means the sum of every group of 6 terms = 0. SInce we want the sum of the first 36 terms, 36/6 is 6 group of 6. 6*0 = 0.
The sum = 0, or choice [A]
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