Yesterday, Integrated Learning posted a 700 level GMAT question on our blog. Today, they have followed-up with the answer:
In the GMAT, if you are asked to work with a very distant term in a sequence, you need to look for a pattern (you wouldn’t write out all 700 terms!). In all cases like this, you need to solve out the first few terms in the sequence and look for a pattern. In this case, the terms of this sequence are:
Term 1: -2
Term 2: 2
Term 3: 4
Term 4: 2
Term 5: -2
Term 6: -4
Term 7: -2
You will see that after the 6th term, the sequence repeats, and every 6 terms, the sum is 0. Therefore, every time the sequence repeats, the sum will be 0.
Now, find out how many times 6 goes into 700 and you’ll have your answer. 700 divided by 6 is 116 R4. The 700th term is 4 more than the last set of 6, so it’s the sum of the first four terms, or 6.
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