Question

For an Ap sum of first n terms=979
d=-5, n=22, thenvalue of a is.​

Answer 1

Answer:

-3.

Step-by-step explanation:

Here,

a=22,l=−11,S  

n​ =66

Therefore,

Sn =  2n  

(a+l)=66

211n

​  

=66

n=12

Now, last term, l=a+(n−1)d=−11

22+11d=−11

d=−3

Therefore, number of terms of the AP is 12 and the common difference is -3.