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प्रश्न
Find n if `""^6"P"_2 = "n" ""^6"C"_2`
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उत्तर
`""^6"P"_2 = "n" ""^6"C"_2`
∴ `(6!)/((6 - 2)!) = "n"(6!)/(2!(6 - 2)!)`
∴ `(6!)/(4!) = "n"(6!)/(2!4!)`
∴ n = 2! = 2 × 1 = 2
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