Prove : ` nPr = n (n-1)P(r-1)` – InterviewSolution

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1.	Prove : ` nPr = n (n-1)P(r-1)`
Answer» `.^nP_r=.^nC_rr!` `=(n!)/((n-r)!r!)r!` `=(n!)/(n-r)!`. `=n (n-1)!(r-1)!` `=n(n-1)C_(r-1)(r-1)!` `n*(n-1)P_(r-1)`

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