If `a_1 =2 and a_n-a_(n-1)=2n (n>=2)`, find the value of `a_1 + a_2 + a_3+ .....+ a_20`

If a_1+a_2+a_3+......+a_n=1 AA a_1 > 0, i=1,2,3,......,n, then find the maximum value of a_1 a_2 a_3 a_4 a_5......a_n.

If a_1+a_2+a_3+......+a_n=1 AA a_i > 0, i=1,2,3,......,n , then find the maximum value of a_1 a_2 a_3 a_4 a_5......a_n .

If a_1+a_2+a_3+......+a_n=1 AA a_i > 0, i=1,2,3,......,n , then find the maximum value of a_1 a_2 a_3 a_4 a_5......a_n .

If a_(n) = n(n!) , then what is a_1 +a_2 +a_3 +......+ a_(10) equal to ?

FOr an integer nlt2, we have real numbers a_1,a_2,a_3,a_4,..........,a_n such that a_2+a_3+a_4+.......+a_n=a1 and a_1+a_3+a_4+...........+a_n=a_2...............a_1+a_2+a_3+..............+a_(n-1)=a_n what is the value of a_1+a_2+a_3+........+a_n?

Three distinct numbers a_1 , a_2, a_3 are in increasing G.P. a_1^2 + a_2^2 + a_3^2 = 364 and a_1 + a_2 + a_3 = 26 then the value of a_10 if a_n is the n^(th) term of the given G.P. is:

{a_n} and {b_n} are two sequences given by a_n=(x)^(1//2^n) +(y)^(1//2^n) and b_(n)=(x)^(1//2^n)-(y)^(1//2^n) for all n in N. The value of a_1 a_2 a_3……..a_n is equal to

If a_i > 0 for i=1,2,…., n and a_1 a_2 … a_(n=1) , then minimum value of (1+a_1) (1+a_2) ….. (1+a_n) is :

Let a_1,a_2,a_3,.... are in GP. If a_n>a_m when n>m and a_1+a_n=66 while a_2*a_(n-1)=128 and sum_(i=1)^n a_i=126 , find the value of n .