If the sum of `n` terms of an A.P. is `c n(n-1)` where `c!=0,` then the sum of the squares of these terms is `c^2n(n+1)^2` b. `2/3c^2n(n-1)(2n-1)` c. `(2c^2)/3n(n+1)(2n+1)` d. none of these

If the sum of first n terms of an A P is c n^2, then the sum of squares of these n terms is (2009) (n(4n^2-1)c^2)/6 (b) (n(4n^2+1)c^2)/3 (n(4n^2-1)c^2)/3 (d) (n(4n^2+1)c^2)/6

If the sum of first n terms of an AP is cn^(2) , then the sum of squares of these n terms is (2009)( a) (n(4n^(2)-1)c^(2))/(6) (b) (n(4n^(2)+1)c^(2))/(3) (c) (n(4n^(2)-1)c^(2))/(3) (d) (n(4n^(2)+1)c^(2))/(6)

The sum of n terms of an A.P. is 3n^(2)+n then its pth term is (A)6P+2(B)6P-2(C)6P-1 (D) none of these

If the n^(t h) term of an A.P. is 2n+1 , then the sum of first n terms of the A.P. is n(n-2) (b) n(n+2) (c) n(n+1) (d) n(n-1)

If the n^(t h) term of an A.P. is 2n+1 , then the sum of first n terms of the A.P. is n(n-2) (b) n(n+2) (c) n(n+1) (d) n(n-1)

If the sum of n terms of an A.P. is 2n^2+5n ,\ then its nth term is a. 4n-3 b. 3n-4 c. 4n+3 d. 3n+4

In a sequence of (4n+1) terms, the first (2n+1) terms are n A.P. whose common difference is 2, and the last (2n+1) terms are in G.P. whose common ratio is 0.5 if the middle terms of the A.P. and LG.P. are equal ,then the middle terms of the sequence is (n .2 n+1)/(2^(2n)-1) b. (n .2 n+1)/(2^n-1) c. n .2^n d. none of these

In a sequence of (4n+1) terms, the first (2n+1) terms are n A.P. whose common difference is 2, and the last (2n+1) terms are in G.P. whose common ratio is 0.5 if the middle terms of the A.P. and LG.P. are equal ,then the middle terms of the sequence is (n .2 n+1)/(2^(2n)-1) b. (n .2 n+1)/(2^n-1) c. n .2^n d. none of these

Find sum of sum_(r=1)^n r . C (2n,r) (a) n*2^(2n-1) (b) 2^(2n-1) (c) 2^(n-1)+1 (d) None of these

The sum of n terms of a series is An^(2)+Bn then the n^(th) term is (A) A(2n-1)-B(B)A(1-2n)+B(C)A(1-2n)-B(D)A(2n-1)+B