Hi I need help solving:
The sum \[6(1⋅3+2⋅4+⋯+n(n+2))\] is equal to a polynomial f(n) for all n≥1. Write f(n) as a polynomial with terms in descending order of n.
Thank you!!
The answer is f(n) = 4n^3 + 5n^2 + 9n.
+36 
