Question

Find the sum of the first 8 terms of the sequence. Show all work for full credit.

1, -3, -7, -11, ...

Answer 1

There are only four terms here. It says we need 8?

Answer 2

Oh, yeah! I figured out that the 8 terms are: 1, -3, -7, -11, -15, -19, -23, and -27, because you subtract 4 from each previous number! Now, can you help? (:

Answer 3

Yes, So here we are really just adding all of the negatives and adding one. So lets just pretend the negatives are positive and then make the sum negative. We have -105 and we have to add the positive one so we have -104. Does that make sense?

Answer 4

Oh my goodness, never mind! I just figured it out by using the formula Sn = n/2(a1 + a[n])! Thank you for trying to help out though! I got it! (: haha

Answer 5

Ok I thought it was a more simple problem. Glad you got it!