Question: we will prove the statement by contradiction let a ...

We will prove the statement by contradiction. Let A = {nx : n ∈ N}, and suppose that A is bounded above by y. (a) Let z = lub(A). Explain why for any r < α there exists some n ∈ N such that r < nx

We will prove the statement by contradiction. Let A = {nx : n ∈ N}, and suppose that A is bounded above by y.

(a) Let z = lub(A). Explain why for any r < z there exists some n ∈ N such that r < nx