please answer the following questions showing working

3. Convert the following functions to Big-O: 10n + O(Ig(n)), 0.25n! + 2n, 1+2+3, 5 log(n), log(n^2) + 100 4. For all the code you write for other problems in this review, compute (a) the function which describes the time your function will take to run and (b) the Big- O of the function. Make sure to state what your variables mean (e.g. "what is n?"). 5. What's the difference between "best case", "worst case", and "average case" Big- O? 6. Explain the formal definition of Big-O: T(n) is O(F(n)) if there are positive constants c and no such that, when n >= no, T(n)