Question

if.npr=1716,ncr=286,find n and r

Answer 1

n!/(n-r)!r!=1716
n!/(n-r)!=286
by dividing
(n!/(n-r)!r!)/n! /(n-r )! =6
r! =6
r =3×2×1 i. E .... r=3

n!/(n-r)!=286
n!/(n-3)! =286
n×(n-1)×(n-2) 286