The value of \[^{n}{{P}_{r}}\] is equal to [IIT 1971; MP PET 1993]

1.	The value of \[^{n}{{P}_{r}}\] is equal to [IIT 1971; MP PET 1993]
A.	\[^{n-1}{{P}_{r}}+r{{\,}^{n-1}}{{P}_{r-1}}\]
B.	\[n.{{\ }^{n-1}}{{P}_{r}}{{+}^{n-1}}{{P}_{r-1}}\]
C.	\[n{{(}^{n-1}}{{P}_{r}}{{+}^{n-1}}{{P}_{r-1}})\]
D.	\[^{n-1}{{P}_{r-1}}{{+}^{n-1}}{{P}_{r}}\]
Answer» B. \[n.{{\ }^{n-1}}{{P}_{r}}{{+}^{n-1}}{{P}_{r-1}}\]

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The value of \[^{n}{{P}_{r}}\] is equal to [IIT 1971; MP PET 1993]

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