Asymptomatic Big O Notation

MY QUESTION IS -> I understand when you plug in n=1 1 -> 2 isn't

BUT WHEN YOU PLUG IN 2 : 2.90 ISNT =2???

Example 4.11: 3logn+2 is O(logn) Justification: 3logn+25logn, for n2. Note that logn is zero for n=1. That is why we use nn0=2 in this case