- #1
Felafel
- 171
- 0
Hello everyone,
I found this exercise on the internet:
find the supremum and infimum of the following set A1, where
A1 = {2(-1)^(n+1)+(-1)^((n^2+n)/2)(2+3/n): n belongs to |N*}
being |N* = |N\{0}
The solution was:
A1 = {-3, -11/2, 5}U{3/4k, -3/(4k+1),-4-3/(4k+2),4+3/(4k+3) : k belongs to |N*}
I don't get the reasoning behind. what's k? why and how did they use it?
I found this exercise on the internet:
find the supremum and infimum of the following set A1, where
A1 = {2(-1)^(n+1)+(-1)^((n^2+n)/2)(2+3/n): n belongs to |N*}
being |N* = |N\{0}
The solution was:
A1 = {-3, -11/2, 5}U{3/4k, -3/(4k+1),-4-3/(4k+2),4+3/(4k+3) : k belongs to |N*}
I don't get the reasoning behind. what's k? why and how did they use it?