[" 41.The nth term of an A.P.is "(3+n)/(4)" ,then the sum of "],[" first "105" terms is "]

The nth term of an AP. Is (3+n)/(4) , then the sum of first 105 terms is

If the nth term of an A.P. is t_(n) =3 -5n , then the sum of the first n terms is ………

If the n^(th) term of an A.P.is (2n+1), then the sum of its first three terms is (a) 6n+3 (b) 15 (c) 12 (d) 21

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

If the nth term of an A.P. is 4n-1 , find the 30th term and the sum of first 30 terms.

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

the A.P. nth term of an A.P. is given by (-4n+15). Find the sum of first 20 terms of A.P.