2013Progression (Sequence and Series)Hard
Question
Let 
Then Sn can take value(s)
Then Sn can take value(s)Options
A.1056
B.1088
C.1120
D.1332
Solution
Sn = -12 - 22 + 32 + 42 - 52 - 62 + 72 + 82 .........
Sn = (32 - 12) + (42 - 22) + ............
Sn = 2(1 + 2 + 3 +........ + 4n)
Sn = 4n(4n + 1)
Sn = 4n(4n + 1) = 1056 is possible when n = 8
4n (4n + 1) = 1088 not possible
4n(4n + 1) = 1120 not possible
4n(4n + 1) = 1332 possible when n = 9.
Sn = (32 - 12) + (42 - 22) + ............
Sn = 2(1 + 2 + 3 +........ + 4n)
Sn = 4n(4n + 1)
Sn = 4n(4n + 1) = 1056 is possible when n = 8
4n (4n + 1) = 1088 not possible
4n(4n + 1) = 1120 not possible
4n(4n + 1) = 1332 possible when n = 9.
Create a free account to view solution
View Solution FreeMore Progression (Sequence and Series) Questions
If x is so small that x3 and higher powers of x may be neglected, then may be approximated as...The sum of n terms of the series log a + log + log + ... is-...Let $S = \frac{1}{\sqrt{1} + \sqrt{3}} + \frac{1}{\sqrt{5} + \sqrt{7}} + \frac{1}{\sqrt{9} + \sqrt{11}} + \ldots\frac{1}...If are in A.P. then a,b,c, are also-...The sum of three consecutive terms in a geometric progression is 14. If 1 is added to the first and the second terms and...