If sum of `4^( th )` .`7^( th )` & `10^( th )` term of an A .P .is 15 ,then sum of first thirteen terms of same A.P.is

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

If the n^(th) term of an A.P.is (2n+1), find the sum of first n terms of the A.P.

If n^(th) term of an A.P.is 2n+1. Find the sum of n term.

If the 10 th term of an A.P.is 21 and the sum of its first ten terms is 120, find its nth term.

If p^(th) term of an A.P.is q and the q^(th) term is p .Find the first term of the A.P.

If 10 xx the 10 th term of an A.P.is equal to 15 xx the 15 th term,show that 5 th term of the A.P.is zero.

The sum of the 4^(th) and 8^(th) terms of an A.P. is 24 and the sum of the 6^(th) and 10^(th) terms is 44. Find the first three terms of the A.P.

The 19 th term of an A.P.is equal to three xx its 9 th term is 19, find the A.P.

The sum of the 4^(th) and 8^(th) terms of an AP is 24 and the sum of its 6^(th) term and 10^(th) term is 44. Find the first three terms of the AP.

If 10 xx the 10th term of an A.P.is equal to 15 xx the 15th term,show that 25th term of the A.P.is zero.