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PROVE THAT nPr=n-1Pr+rn-1Pr-1THIS IS ONLY FOR WHO ARE IN 11 CLASS,PLEASE DON'T ANSWER OTHERS |
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Answer» R.H.S (N-1)!/(n-1-r)!+r.(n-1)!/(n-r)! =(n-1)!/(n-r-1)!+r.(n-1)!/(n-r)(n-r-1)! =(n-1)!/(n-r-1)!+(1+r/n-r) =(n-1)!/(n-r-1)!(n/n-r) =n!/(n-r)! =NPR |
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