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For a positive integer n if the mean of the binomial coefficients in the expansion of `(a + b)^(2n - 3)` is 16 Then n is equal toA. 4B. 5C. 7D. 9 |
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Answer» Correct Answer - b The binomail ceofficients in the expansion of `(a + b)^(2n-3) are ""^(2n-3)C_(0)""^(2n-3)C_(1),...,... ""^(2n-3)C_(2n-3)`. It is given that their mean is 16 `therefore (""^(2n-3)C_(0)+""^(2n-3)C_(1) + .........+ ""^(2n-3)C_(2n-3))/(2n-2)= 16` `rArr 2^(2n-3) = 16 (2n -2)` `rArr 2^(2n-8) = 11 -1` `rArr n= 5` (By inspection) |
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