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How many terms of the G.P. 1,2,4…… must ...

How many terms of the G.P. 1,2,4…… must be taken to make the sum 255?

Text Solution

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`a=1,r=2,S_(n)=255,n=`?
`S_(n)=(a(r^(n)-1))/(r-1)rArr255=(1(2^(n)-1))/(2-1)rArr255=2^(n)-1`
`rArr256 =2^(n)rArr2^(8)=2^(n)rArrn=8`
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