Here's the question:
$\sum_{i=1}^{n} \frac{1}{i^2 + i}$
How do you express this summation in terms of n?
I'm at a loss of where to go with this. I know the formulas for the summation of $i^2$ and $i$, but I'm not sure where to use these (or if it's even relevant) because the only thing I can think of is to sum the denominators and then take their reciprocal, which is clearly wrong.