JAMB - Mathematics (1980 - No. 17)

Which of the formula below represents the general terms of the following set of numbers(-1, \(\frac{2}{3}\), -\(\frac{1}{2}\), \(\frac{2}{5}\)......) for n = 1, 2, 3, 4.......?
\(\frac{2}{n + 1}\)
(-1)n + 1 \(\frac{2}{n + 1}\)
(-1)n \(\frac{2}{n + 1}\)
\(\frac{n}{2n - 1}\)
(-1)n\(\frac{n}{2n - 1}\)

Explanation

(-1, \(\frac{2}{3}\), -\(\frac{1}{2}\), \(\frac{2}{5}\)......)

nthterm is (-1)n\(\frac{2}{n + 1}\)

Since (-1)n will always be negative for n = odd

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