defence exam Agniveer Vayu Group X & XY Mock Test 01/2026 Mathematics Sequences and Series Special Series
If the sum of first 'n' natural numbers is \(\frac{n(n+1)}{2}\). Then, what will be the sum of first 'n' terms of the series of alternate positive and negative numbers when 'n' is even?
12 - 22 + 32 - 42 + 52 - ...
I. \(\frac{n(n+1)}{2}\)
II. \(\frac{n^2(n+1)}{2}\)
III. \(\frac{-n(n+1)}{2}\)
Which of the above statement(s) is/are correct?
1
Only I
2
Only III
3
Only II
4
None of these