Tuesday, July 13, 2010

Sequences & Series

Finished AP GP from GMATClub's Math Book. Since we've done AP GP quite extensively in school, concepts are pretty clear to me. It's mostly just formulae otherwise.
Putting this in here because it won't be found everywhere:
"There are some short cuts and concepts that you should know about this topic.

(1) The mean and the medium of any arithmetic sequence is equal to the average of the first and last terms.
(2) The sum of an arthritic sequence is equal to the mean (average) times the number of terms.
(3) The product of n consecutive integers is always divisible by n! So, 4x5x6 (4*5*6=120) is divisible by 3!
(4) If you have an odd number of terms in consecutive set, the sum of those numbers is divisible by the number of terms.
(5) (4) above does not hold true for consecutive sets with an even amount of terms."

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