I know that for positive monotonically non-decreasing functions, f(n) and g(n),
f(n) = O(g(n) + c) entails f (n) = O(g(n))
Why is this always true only for positive monotonically non-decreasing functions? $\Theta$
If there exists one, give a counter-example that shows that the above Big O rule is not necessarily true for functions that are not monotonically non-decreasing.
I'm really confused why the rule specifies only positive, monotonic, non-decreasing functions. Thanks for your help!