Question

How do you find the sum of `Sigma 5` where k is [1,5]?

Answer 1

`sum_"k=1,5" k = 15`

Explanation:

The sum of the first `k` natural numbers is given by: `(k(k+1))/2`

Hence: `sum_"k=1,5" k = (5(5+1))/2 = (5*6)/2 = 15`