InterviewSolution
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InterviewSolution
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The value of `sum_(r=1)^(15) (r2^(r))/((r+2)!)` is equal toA. `((17)!-2^(16))/((17)!)`B. `((18)!2^(17))/((18)!)`C. `((16)!-2^(15))/((16)!)`D. `((15)!-2^(14))/((15)!)` |
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Answer» Correct Answer - A `(rxx2^(r))/((r+2)!) = ((r+2-2)2^(r))/((r+2)!)` `= (2^(r))/((r+1)!)-(2^(r+1))/((r+2)!)` `= - ((2^(r+1))/((r+2)!)-(2^(r))/((r+1)!))` `= -(V(r)-V(r-1))` `rArr underset(r=1)overset(15)sum(rxx2)/((r+2)!)=-(V(15)-V(0))` `= - ((2^(16))/(17!)-(2)/(2!))` `= 1-(2^(16))/((17)!)` |
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