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If ""^(n)P(5)=20 ^(n)P(3)"", find the va...

If `""^(n)P_(5)=20 ^(n)P_(3)""`, find the value of n.

Text Solution

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The correct Answer is:
5040
`(n!)/((n-5)!)xx((n-3)!)/(n!)=20`
or (n-3)(n-4)=20
or n=-1,8
But -1 is not acceptable.
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