Please give me some ideas about this question....

Suppose by carful measurement we have discovered a function that describes the precise running time of some algorithm. For each of teh following such functions, discribe the algorithmic running time in big-Oh notation:

A. 3n2 + 3n + 7

B. (5*n) * (3 + log n)

C. (5n+4)/ 6

D. 1+2+3+ ..... +n

E. n + log n2

F. (n+1) log n / 2

Please help me ...

Thank you...