Question

Find the sum of all 11 terms of an A.P. whose middle most
term is 30.​

Answer 1

Answer:

let a is the 1st term and d is the common difference

so,sum of the 11 terms is

1/2{2a+(11-1)d}

=1/2(2a+10d)

=1/2*2(a+5d)

=a+5d

middle most term of the series of 11 terms is 6th term

6th term =a+(6-1)d=a+5d=30

so,the sum of the 11 terms is a +5d=30