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The valur of `sum_(r=0)^(n) sum_(p=0)^(r) ""^(n)C_(r) . ""^(r)C_(p)` is equal toA. `3^(n) - 2^(n)`B. `3^(n) - 2^(n) - 2`C. `3^(n) - 2^(n) + 2`D. none of these |
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Answer» Correct Answer - d We have , `sum_(r=0)^(n) sum_(r=0)^(n) ""^(n)C_(r) . ""^(r)C_(p)` `sum_(r=0)^(n) ""^(r)C_(p) (sum_(r=0)^(n) ""^(n)C_(p)) = sum_(r=0)^(n) . ""^(n)C_(r) 2^(r) = (1 +2)^(n) = 3^(n)` . |
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