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.
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.