Question

Find Sn for the given arithmetic series. Q1 = -40, d =-7, n=22

Answer 1

Answer:

$S_n =$ -2497

Step-by-step explanation:

We are given an arithmetic series with the following terms:

First term, $Q_1$ = -40

Common difference, d = -7

Number of terms, n = 22

To find out: Sum of n terms, where n is 22

We know that Sum of n terms in an arithmetic series is given as:

$S_n =\dfrac{n}{2} (2Q_1+(n-1)d)$

Putting the values in the formula:

$S_{22} = \dfrac{22}{2} (2 \times -40+(22-1)\times (-7))\\\Rightarrow S_{22} = 11 \times (-80-147)\\\Rightarrow S_{22} = 11 \times (-227)\\\Rightarrow S_{22} = -2497$

So, the sum of 22 terms is -2497.