Question

How do you do a problem like this? We haven't done this in my class yet. I'm just trying to get a head start.

Answer 1

do you know how to do combinatorics?

Answer 2

nope lol

Answer 3

This is called Series. This is basically what you do. You start at 1 as indicated below the sigma sign (the pointy E sign). Sub in 1 for k and then sub in 2 for k, adding the terms as you go along. Stop at 5 since it's written at the top of the sigma sign. Do you kind of understand? My explanation isn't too great but hopefully by the picture you'll get it?