In the A.P. `1,\ 7,\ 13 ,\ 19 ,\ dot,\ 415` prove that the sum of the middle terms is equal to the sum of first and last terms.

In the A.P.1,7,13,19, ; 415 prove that the sum of the middle terms is equal to the sum of first and last terms.

7th term of an A.P. is 40. then the sum of the first 13 terms is

What is the sum of first ten terms of the A.P., if the first term is 1 and the last term is 19 ?

7^(th) term of an A.P. is 40. Then, the sum of first 13 terms is

In an A.P. the ratio of 7th term to 11th term is 19 : 31 and the sum of these two terms is 20.Find the sum of first twenty terms.

If 12th term of an A.P. is -13 and the sum of the first four terms is 24, what is the sum of first 10 terms ?

If 12th term of an A.P. is -13 and the sum of the first four terms is 24, what is the sum of first 10 terms ?

In an A.P, the first term is 1 and sum of the first p terms is 0, then sum of the first (p + q) terms is

In an A.P., if 1 is the first term and the sum of the are 1 first p terms is zero, then the sum of the next q terms is

Prove that in an A.P. of finite number of terms the sum of any two terms equidistant from the beginning and the end is equal to the sum of the first and last terms.