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Home  >>  CBSE XI  >>  Math  >>  Sequences and Series
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Find the first $5$ terms of the sequence whose general term is $t_n=(-1)^{n-1}.\:5^{n+1}$

$\begin{array}{1 1}25,125,625,3125,15625 \\25,-125,625,3125,15625 \\ 25,125,625,-3125,15625 \\ 25,-125,625,-3125,15625 \end{array} $

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Given: $t_n=(-1)^{n-1}.\:5^{n+1}$
By putting $n=1,2,3.....$ we get the first 5 terms as
$t_1=(-1)^{1-1}.\:5^{1+1}=25$
$t_2=(-1)^{2-1}.\:5^{2+1}=-125$
$t_3=(-1)^{3-1}.\:5^{3+1}=625$
$t_4=(-1)^{4-1}.\:5^{4+1}=-3125$
$t_5=(-1)^{5-1}.\:5^{5+1}=15625$
answered Feb 17, 2014 by rvidyagovindarajan_1
 

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