Thursday, May 3, 2007

Prompt

Sir I know its late, but i just noticed i posted it wrong and it did not appear. I dont know if you will acccept it but i'll try. sorry!

1. Question on the topic?
The question i have was how can you figure out the rate in a geometric formula when given two tems?

2. WHat mistakes are you most likely ot make?
most likely i would make mistakes in wirting the explicit formula because ui get confused on whre tn should go because the common formulas have t1 and the explicit ones do not.

3. example
write wether arithmetic, geomteric o none and make an equation for the sequence.
3,6,9,12,15

solution: arithmetic
Tn= 3 + (n-10) 3
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2 comments:

anto said...
This comment has been removed by the author.
May 3, 2007 at 1:49 PM
anto said...

To find r in a geometric series given two terms you just need to divide the second term by the first one. For example, in the geometric series 2,8,32 the rate is 4 since (8/2) = 4 and (32/8) also equals 4.

The series you came up with 3,6,9,12,15 is an arithmetic series, however the formula you displayed as the answer isn't quite right. Remember that the formula for an arithmetic series is:

Tn = T1 + (n-1)D

In this case d=3 and t1 also equals 3, therefore the final formula is:

Tn = 3 + (n-1)3

A useful tip is to always check the formula you come up with, if you plugged in one for n and solved using your formula you would get -24 when in fact the first term is 3

May 3, 2007 at 1:57 PM

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