Big O Notation of an expression

Question

If I have an algorithm that takes 4n^2 + 7n moves to accomplish, what is its O? O(4n^2)? O(n^2)?

I know that 7n is cut off, but I don\'t know if I should keep the n^2 c

Answer 1

The coefficients aren't relevant in Big O notation, so it's just O(n²). As Wikipedia explains:

[...] the coefficients become irrelevant if we compare to any other order of expression, such as an expression containing a term n³ or n².