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Prove that (n!)/(r!(n-r)!)+(n!)/((r-1)!(...

Prove that `(n!)/(r!(n-r)!)+(n!)/((r-1)!(n-r+1)!)= ((n+1)!)/ (r!(n-r+1)!)`.

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MODERN PUBLICATION-PERMUTATIONS AND COMBINATIONS-EXERCISE
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  2. If (n!)/(2!(n-2)!):(n!)/(4!(n-4)!) =2:1. Find the value of n.

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  3. Prove that (n!)/(r!(n-r)!)+(n!)/((r-1)!(n-r+1)!)= ((n+1)!)/ (r!(n-r+1)...

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