Question

I really don't understand and I would greatly appreciate it if you could show all work pls. I want to see all work. Thanks!!!!

Showing the work would be great!

9. Calculate the sum に! 5k- 2 k-1 cos(k)- e-1 (3k-2) = k-1 2k(k 12)- に!

Show transcribed image text 9. Calculate the sum に! 5k- 2 k-1 cos(k)- e-1 (3k-2) = k-1 2k(k 12)- に!