Question

The permutations and combinations of Abcd taken 3 at a time are respectively

Answer 1

formula of permutation=p=npr=n!/(n-r)!

formula of combination=c=ncr=n!/r!(n-r)!

given =n=4

and r=3

npr=4!/(4-3)!

npr=4*3*2

npr=24

ncr=n!/R!(n-r)!

ncr=4!/31(4-3)!

ncr=4.3!/31(4-3)!

ncr-4