The function 4n + 6 can be said to belong to O(n³). I want to know
Why is this false?
I am new to data structure. I will be really glad if someone can explain it to me.
Big-O is an upper bound, not a tight bound. If you have ten dollars in your pocket and tell your friend "I have an amount of money in my pocket, and it's no more than a million dollars", you're telling the truth, but you're not giving them terribly accurate information.
Likewise, the function f(n) = 4n + 6 is technically in O(n^3); it's also in O(n^2), O(2^n), and O(n!), but the most accurate upper bound is O(n).