Write the sum using summation notation, assuming the suggested pattern continues.

-9 - 4 + 1 + 6 + ... + 66

Question

Write the sum using summation notation, assuming the suggested pattern continues.

-9 - 4 + 1 + 6 + ... + 66

anonymous · Answer

attachment

anonymous · Answer

how do i solve this

anonymous · Answer

is it the first one

anonymous · Answer

I think the 3rd one is correct if the sequence continue to infinitive

anonymous · Answer

because if it stops there, the term 13th =66, but the notation on sum sign go from 0 to 15. it is contradiction

lyrae · Answer

The sequence is arithmetic so$$a_{n} = 5n-9$$$$a_{n} = 5n-9 \rightarrow n= (a_{n} +9)/5 = 15 $$$$\sum_{i=0}^{n} (a_{n}) = \sum_{i=0}^{15} (5 i - 9)$$ http://www.wolframalpha.com/input/?i=-9+-+4+%2B+1+%2B+6+%2B+...+%2B+66

anonymous · Answer

yes, Lyrae is right, I'm sorry, my bad.