Question

prove that this question

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Answer 1

Answer:

Step-by-step explanation:

ⁿPr=n!/(n-r)!...........................(1)

Putting n=n-1 and r=r-1

ⁿ⁻¹Pr-1=(n-1)!/{ n-1-(r-1) }

We know that n!=n*(n-1)!, So (n-1)!,=n!/n

So ⁿ⁻¹Pr-1=n!/n/{ n-1-r+1)! }

=n!/ n*(n-r)!

Putting n!/(n-r)!=ⁿPr

ⁿ⁻¹Pr-1 =1/n( ⁿPr)

Hence ⁿPr=n* ⁿ⁻¹Pr-1

Proved