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Q)

$15C_8+15C_9-15C_6-15C_7$=_____

$\begin{array}{1 1}(A)\;0\\(B)\;1\\(C)\;2\\(D)\;3\end{array} $

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A)
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  • $nC_r=\large\frac{n!}{r!(n-r)!}$
$nC_r+nC_{r+1}-nC_r-nC_{r+1}$
$\Rightarrow 0$
Hence (A) is the correct answer.
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