Question

The sum of the first n positive integers is 1/2 (n2 + n). Check the expression for the first 5 positive integers. Then use the expression to find the sum of the first 14 positive integers.

Answer 1

second part, compute \[\frac{14\times 15}{2}\]

Answer 2

You already have the formula.
All you need to do is to substitute the value of n with 14.