SOLUTION: John saves Nu. 2 in january, Nu. 6 in february, Nu. 18 in march and so on. The total saving in one year by John is how much?

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Question 624868: John saves Nu. 2 in january, Nu. 6 in february, Nu. 18 in march and so on. The total saving in one year by John is how much?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

John saves Nu. 2 in january, Nu. 6 in february, Nu. 18 in march and so on.

 a%5Bn%5D+=+a%5B1%5D%2Ar%5E%28n-1%29 , r = 3

 a%5Bn%5D+=+2%2A3%5E%28n-1%29

S%5Bn%5D+=++a%5B1%5D%28%281-r%5En%29%2F%281-r%29%29

S%5B12%5D+=++2%28%281-3%5En%29%2F%28-2%29%29=+531440