What is the best (tightest) upper bound, i.e., f(n) = O(?) for the following functions?

f(n)=12n4+15n3+21n2+28n+35f(n)=(n2+2)(n+1)f(n)=(n+2)(n2+9)f(n)=3+6n+9n2n3logn+2n5f(n)=i=1n(n+i4)

2 + + 35 n 310g n + 5 2n 2 4)