is equal to
n
1/n
1/2 (n+n-1)
1/2 (en + e-n)
If three numbers a,b,c are in harmonic progression, then which of the following is true?
1/a, b, 1/c are in AP
1/bc, 1/ca, 1/ab are in HP
ab, bc, ca are in HP
a/b, b/c, c/a are in HP
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
3
5
9
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
The value of 91/3 × 91/9 × 91/27 × ...... is
1
None of these
In an arithmetic progression, the 24th term is 100. Then, the sum of the first 47 terms of the arithmetic progression is
2300
2350
2400
4700
The 5th term of the series is
1/3
2/5
If y = 1 + x + x2 + x3 + .... then x is equal to
y-1/y
1-y/y
y/a-y
The arithmetic means of first n odd natural number is
n2
2 n
3 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
