If w 1 is a cube root of unity, then the sum of the series S = 1 + 2w + 3w2 + ... + 3nw3n -1 is
3n(w - 1)
0
If in a . ABC, sin(A), sin(B), sin(C) are in AP, then
the altitudes are in AP
the altitudes are in HP
the angles are in AP
the angles are in HP
If sum of an infinite geometric series is 4/3 and its Ist term is 3/4, then its common ratio is
7/16
9/16
1/9
7/9
A.
7/16
We know that sum of infinite geometric series
=
where a = first term and r = common ratio.
Then,
Sum of n terms of the following series 13 + 33 + 53 + 73 + ... is
n2(2n2 - 1)
n3(n - 1)
n3 + 8n + 4
2n4 + 3n2