MATH question

[joonkimdds]

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1, 2, 1, -1, -2 .....

The first five terms of a sequence are shown above. After the 2nd 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 2nd term. What is the sum of the 1st 36 terms of the sequence?

a) 0
b) 4
c) 12
d) 24
e) 30

 

[pbure9]

I'll give this a shot.

You basically develop a pattern:

1, 2, 1, -1, -2, -1, 1, 2, 1.. and then you realize it repeats over and over again

1, 2, 1, -1, -2, -1 then it starts over

that's 6 numbers. So take the sum of that and multiply by 6 to get up to 36 numbers in the sequence.
However, the sum of those 6 is 0. So its 0 for the sequence

Let me know if that helps, or whether or not I'm right =P

 

[joonkimdds]

u r right 🙂 ty

 

[pbure9]

u r right 🙂 ty

w00t. when i first looked at that i was like

but its not that bad. 😀