Answer:
[tex]S_n =[/tex] -2497
Step-by-step explanation:
We are given an arithmetic series with the following terms:
First term, [tex]Q_1[/tex] = -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:
[tex]S_n =\dfrac{n}{2} (2Q_1+(n-1)d)[/tex]
Putting the values in the formula:
[tex]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[/tex]
So, the sum of 22 terms is -2497.
