Let us suppose that there exists a natural number n satisfying the following condition: (n/(n+1))≤(n/(n+2)). Then
n(n+2)≤n(n+1) ⇔ n(n+2)-n(n+1)≤0 ⇔ n≤0
Thus, 0≥n≥1 and 0≥1. Which is absurd.
Let us suppose that there exists a natural number n satisfying the following condition: (n/(n+1))≤(n/(n+2)). Then
n(n+2)≤n(n+1) ⇔ n(n+2)-n(n+1)≤0 ⇔ n≤0
Thus, 0≥n≥1 and 0≥1. Which is absurd.