Let a = for n = 1, 2, 3 . . . then the greatest value of n for which an is the greatest is
11
20
10
8
C.
10
Given, , n = 1, 2, 3 . . . , here we see
that when we increase the value of n like as 1, 2, 3 . . . the value of a, increases but when we reach at n = 9 or 10 the value of an remain unchanged, ie, minor difference in after decimal places and when we cross the value n = 10 ie, n = 11, then we see that the value of a, is monotonically decreasing.
Hence, an have its maximum value at n = 9 or 10.
If a, b and c form a geometric progression with common ratio r, then the sum of the ordinates of the points of intersection of the line ax + by + c = 0 and the curve x + 2y2 = 0 is
r
If pth, qth, rth terms of a geometric progression are the positive numbers a, b and c respectively,then the angle· between the vectors (log(a))2i + (log(b))2j + (log(c))2k and (q - r)i + (r - p)j + (p - q)k is