If `16. nP_3=13. n+1P_3` then prove that n=15

If nP_(13):(n+1)P_(12)=3:4 then prove that n=15

If "^nP_5 = 20. "^nP_3 then n =

If P_(m) stands for mP_(m), then prove that: 1+1.P_(1)+2.P_(2)+3.P_(3)+...+n.P_(n)=(n+1)!

If quad simquad nP_(4):^(n)P_(5)=1:2 then prove that n=6

If P_(n) is the sum of a G.P. upto n terms (n>=3), then prove that (1-r)(dP_(n))/(dr)=(1-n)P_(n)+nP_(n-1), where r is the common ratio of G.P.

If ^ n P_5 = 20 ^nP_3 find the value of n

If "^nP_5 = 60xx "^(n-1)P_3 ,then n =

If ""^nP_4=5 ""^nP_3 , then n is :