Converting an explicitly defined function to a recursive one In studying for an exam, I had difficulty with these two questions:

Give a recursive form (including bases) for the following functions.
$$f(n) = 5 + (-1)^n$$
$$f(n) = n(n+3)$$


HINT $\rm\ \ (-1)^{n+1}/(-1)^n = -1,\ $ so substituting $\rm\ (-1)^n\ =\ f(n)-5\ \Rightarrow\ \ldots$  
For the second, note that $\rm\ f(n+1) - f(n)\ $ reduces the degree of polynomial $\rm\ f(n)\:$.
