Sum of Series Using Standard ResultsWatch
I assumed it was inside - they hadn't used any brackets so it's a bit unclear?
Looking at the numbers, it Is guess +6b may make more sense, but will check now.
- Study Helper
They may just want you to sub a few values in?
Other questions have just been about substituting for the standard results where the sigma notation is - pre-method of differences?
Understanding a) and c) is not too hard as c) is the square of triangular numbers (a) with different index which you can do a bit of reasoning about. Possibly beyond what is required.