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If the first term of a G.P. be 5 and common ratio be -5 , then which term is 3125
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Verified Answer
The correct answer is:
$5^{\text {th }}$
Given that first term $a=5$ and common ratio $r=-5$. Suppose that $n^{\text {th }}$ term is 3125 ,
then $a r^{n-1}=3125 \Rightarrow 5(-5)^{n-1}=3125 \Rightarrow(-5)^{n-1}=5^4$
Hence $n=5$.
then $a r^{n-1}=3125 \Rightarrow 5(-5)^{n-1}=3125 \Rightarrow(-5)^{n-1}=5^4$
Hence $n=5$.
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