Number of points of intersection of `n` straight lines if `n` satisfies `n+5P_(n+1)=(11(n-1))/2xx^(n+3)P_n` is a. `15` b. `28` c. `21` d. 10

If "^(n+5)P_(n+1) = (11(n-1))/2"^(n+3)P_n , find ndot

The number of positive integers satisfying the inequality C(n+1,n-2) - C(n+1,n-1)<=100 is

The number of positive integers satisfying the inequality C(n+1,n-2)-C(n+1,n-1)<=100 is

Straight lines are drawn by joining m points on a straight line of n points on another line. Then excluding the given points, the number of point of intersections of the lines drawn is (no tow lines drawn are parallel and no these lines are concurrent). a. 4m n(m-1)(n-1) b. 1/2m n(m-1)(n-1) c. 1/2m^2n^2 d. 1/4m^2n^2

Find n if : ""^(2n+1) P_(n-1) : ""^(2n-1) P_n = 3: 5

If 2n+1P(n-1) : (2n-1)Pn =3:5,find n

The sum of first n odd natural numbers is 2n-1 (b) 2n+1 (c) n^2 (d) n^2-1

If S_n denotes the sum of first n terms of an A.P. and (S_(3n)-S_(n-1))/(S_(2n)-S_(2n-1))=31 , then the value of n is a. 21 b. 15 c.16 d. 19

Number of positive terms in the sequence x_n=195/(4P_n)-(n+3p_3)/(P_(n+1)), n in N (here p_n=|anglen )

If S_n denotes the sum of first n terms of an A.P. and (S_(3n)-S_(n-1))/(S_(2n)-S_(2n-1))=31 , then the value of n is 21 b. 15 c.16 d. 19