[" ANSWER "],[" We know that: "],[nP_(r)=(n!)/((n-r)!)],[8P_(5)=(8!)/(9)=]

Prove that P(n;r)=nP_(r)=n(!)/(n-r)!

11. Prove that nP_(r)=n(n-1)P_(r-1)

Show that ^(^^)nP_(r)=(n-r+1)^(n)P_(r-1)

Prove that: ""^(n+1)P_(r+1)=(n+1)* ""^nP_r .

Prove that .^nP_r = ^(n-1)P_r + r^(n-1)P_(r-1)

Evaluate (n!)/((n-r)!) n = 9, r = 5

If nP_(r)=5040 then (n,r)=

If the number of permutations of n different things taken r at a time be denoted by nP_(r) show that (nP_(1))/(1!)+(nP_(2))/(2!)+(nP_(3))/(3!)+......+(nP_(n))/(n!)=2^(n)-1

Prove that , ""^nP_r = ""^((n-1))Pr + r. ""^(n-1)P_((r-1))

The value of sum_(r=1)^(n)(nP_(r))/(r!)=