Thread: Arithmetic Sequence - Series Questions

How many terms for the arithmetic sequence {-3,2,7,...} must be added together for the sum of the series to be 116? - SOLVED, Thanks pickslides!


Also;


Find the least value of n for which Sn>10000 for the sequence {3,6,12...}

Finally

A ball is dropped from a height of eight feet. The ball bounces to 80% of it's previous height of each bounce. How high (to the nearest tenth of a foot) does the ball bounce on the fifth bounce?


I know I can logically solve some of these problems with logic, but I need to do it arithmetically. I don't necessarily need these solved, just the appropriate process to go about solving them.

For the first one,

What is a (the first term) and d (the common difference) in your sequence?

Once you know then solve for n.

I get to 116=n/2(5n-11) and I feel like I'm going to end up factoring a quadratic, is that correct?

I have the same feeling.

Alright, so n=8 and n=-29/5. I filled 8 in for n and got 116. You are a great human being for taking the time to help me. Thank you so much for the first answer!