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The sum `1+3+7+15+31+...to100`terms is`2^(100)-102 b`b. `2^(99)-101`c. `2^(101)-102`d. none of theseA. `2^(100)-102`B. `2^(99)-101`C. `2^(101)-102`D. none of these

Answer» Correct Answer - C
Here the successive differences are 2,4,8,16,… which are in G.P.
`S=1+3+7+15+31+…+T_(100)`
`=(2^(1)-1)+(2^(2)-1)+(2^(3)-1)+..+(2^(100)-1)`
`=(2+2^(2)+2^(3)+….+2^(100))-100`
`=2((2^(100)-1)/(2-1))-100`
`=2^(101)-102`


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