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Jamie D
Posts:
41
Registered:
9/17/13


Re: Common Core eText Done
Posted:
Mar 21, 2014 8:45 AM


Matt,
The modules are a bit confusing with respect to using just n or (n  1) as some of the problems are mixed up and it depends on what you are given as to which to use.
I tell students that if we are starting with an initial quantity at n = 0 then we use n. Example if you have $5000 in a bank account growing at 5% per year, the explicit formula would be f(n) = 5000(1.05)^n since if we substitute 0 for n, we are left with our initial value of 5000.
When dealing with sequences (and some applications of functions), we start with some initial quantity when n = 1. This is when we use (n  1). So if it's a geometric sequence with the first term of 5000 and common ratio of 1.05, it would look like f(n) = 5000(1.05)^(n1) so when you substitute 1 in for n, 5000 comes out.
It's a bit confusing but all you really have to do is substitute a few values for n into the function to see if you get the values of f(n) you are looking for. Hope that helps......
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