You are given an arithmetic progression (a n), the difference of which is 1.1, a1 = -7. Find the sum of the first 14 members.

We are given an arithmetic progression by the formula (an) by its first term and the difference of the arithmetic progression a1 = -7, d = 11.

In order to find the sum of the first 14 terms of an arithmetic progression, we need to recall the formula for finding the sum of the first n terms of an arithmetic progression through its first term and the difference of an arithmetic progression

Sn = (2a1 + (n – 1) d) / 2 * n;

Let’s write down the formula for finding the sum of the first 14 terms:

S14 = (2a1 + (14 – 1) d) / 2 * 14 = (2 * (-7) + 13 * 1.1) / 2 * 14 = (-14 + 14.3) / 2 * 14 = 0 , 3/2 * 14 = 0.3 * 7 = 2.1.