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The value of `sum_(r=1)^(n+1) (sum_(k=1)^(n) ""^(k)C_(r-1))` (where r,k, n in N`) is equal toA. `2^(n+1)-2`B. `2^(n+1)-1`C. `2^(n+1)`D. none of these |
Answer» Correct Answer - A `underset(r=1)overset(n+1)sum(underset(k=1)overset(n)sum.^(k)C_(r-1))= underset(r=1)overset(n+1)sum(underset(k=1)overset(n)sum(.^(k+1)C_(r)-.^(k)C_(r)))` `= underset(r=1)overset(n+1)sum(.^(n+1)C_(r)+.^(1)C_(r))` `= 2^(n+1) - 2` |
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