1) For a sequence (tn) , if $S_{n}=5(2^{n}-1)$ then tn = ............ A) $5(2^{n+1})$ B) $\frac{5\times 2^{n}}{4}$ C) $5(2^{n-1})$ D) $\frac{2\times (2^{n-1})}{5}$ Answer: Option CExplanation:We have , $S_{n}=5(2^{n}-1)$ We know that , an = Sn -Sn-1 = 5(2n-1)-5(2n-1-1) = 5(2n-2n-1) =$5(2^{n-1})$
