The infinite sequence whose general term is an = 0.17n^2 - 1.02n + 6.67 where n=1,2,3,...,9 models the total operating costs, in millions of dollars, for a company from 1991 through 1999.
find

Question

The infinite sequence whose general term is an = 0.17n^2 - 1.02n + 6.67 where n=1,2,3,...,9 models the total operating costs, in millions of dollars, for a company from 1991 through 1999. 
find

anonymous · Answer

$$\sum_{i=1}^{5}ai$$

anonymous · Answer

i know this is probably simple but because it is in word problem form I can not figure out where to start

klimenkov · Answer

You have to find a sum $$\sum_{i=1}^5(0.17i^2-1.02i+6.67)$$

anonymous · Answer

so do I just place 1,2,3,4,5 in i and solve

klimenkov · Answer

Try to simplify it using
$$\sum_{i=1}^ni^2=\frac{n(n+1)(2n+1)}6$$and
$$\sum_{i=1}^ni=\frac{n(n+1)}2$$

anonymous · Answer

so n is 5 right

anonymous · Answer

or do I still do 1,2,3,4,5 as n and add the results altogether

klimenkov · Answer

You can do anything you like. Just sum all the addends in any way.

anonymous · Answer

I can't seem to get the right answer I got 35 but that is not one of my choices

klimenkov · Answer

Do you have an answer 27.4?

anonymous · Answer

yes

anonymous · Answer

I have always hated word problems they seem to get the best of me

anonymous · Answer

thank you

klimenkov · Answer

No problems. Ask anything you like.