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प्रश्न
Write the first five terms of the sequences whose nth term is:
`a_n = (-1)^(n-1) 5^(n+1)`
उत्तर
an = (−1)n−1 5n+1
Substituting n = 1, 2, 3, 4, 5, we get
a1 = (-1)1 - 1 51 + 1 = (−1)0 52 = 25,
a2 = (-1)2 - 1 52 + 1 = (−1)1 53 = −125,
a3 = (-1)3 - 1 53 + 1 = (−1)2 54 = 625,
a4 = (-1)4 - 1 54 + 1 = (−1)3 55 = −3125,
a5 = (-1)5 - 1 55 + 1 = (−1)4 56 = 15625
The first five terms are 25, −125, 625, −3125, 15625.
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