is equal to
n
1/n
1/2 (n+n-1)
1/2 (en + e-n)
In an AP the sum of any two terms, such that the distance of one of them from the beginning is same as that of the other from the end, is
first term
sum of first and last terms
last term
half of the sum of the series
Geometric mean of 7,72,73,....7n is
7
7n/2
7n
If 2/3, k, 5/8 are in AP, then value of k is
15
21
12
31/48
The value of 91/3 × 91/9 × 91/27 × ...... is
9
3
1
None of these
The sum to infinity of the progression 9 - 3 + 1 -1/3 + .... is
9/2
27/4
15/2
If S is the sum of an infinite GP, the first term a, then the common ratio r is given by
Let a be a positive number such that the arithmetic mean of a and 2 exceeds their geometric mean by 1. Then, the value of a is
5
8
If a, b, c be in arithmetic progression, then the value of (a+2 b - c) (2 b + c - a) (a + 2 b + c) is
16 a b c
4 a b c
8 a b c
3 a bc
If x = 1 + 2 + 4/2! + 8/3! + 16/4! + ...., then x-1 is equal to
e-2
e2
e1/2
