(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Let a(n) and b(n), n[tex]\in[/tex]N, be some real numbers with absolute value at most 1000. Let A={a(n), n[tex]\in[/tex]N}, B={b(n), n[tex]\in[/tex]N}, C={a(n) + b(n), n[tex]\in[/tex]N}. Show that

inf A + sup B [tex]\leq[/tex] sup C [tex]\leq[/tex] sup A + sup B

3. The attempt at a solution

I was thinking that I could show that inf A + sup B = 0, and that sup C is larger than 0, and then that sup C = sup A + sup B. The only problem is that I am terrible at writing formal proofs, and could really use some help with the language, and (probably) my logic.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Sup and inf proof

**Physics Forums | Science Articles, Homework Help, Discussion**