SOLUTION: I need to find the sum of the first n terms of the g.p. 4,12,36... and find the least value of n for which the sum is greater than 500,000.
I know that
r = 3 and a = 4 but then
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Question 328501: I need to find the sum of the first n terms of the g.p. 4,12,36... and find the least value of n for which the sum is greater than 500,000.
I know that
r = 3 and a = 4 but then I am stuck.
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
the formula is:
I'll find out when the sum is greater than 500000
Multiply both sides by
I can take the log of both sides
If , the left side is close to , so
Putting this back into formula,
The next whole number for is
I think that would put over
seems to be too small
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