Question

$\lim_{n\to3} \sum_{r=1}^{n} r^2 =$

Answer 1

14

Answer 2

We first note that

$\lim_{n\to3}\sum_{r=1}^{n} r^2 = \sum_{r=1}^{3} r^2$.

Using the sum,

$1^2 + 2^2 + 3^2 = 1 + 4 + 9 = 14$.