Question

If npr = 2 fonc, = 35 then r =​

Answer 1

Answer:

n

P

r

=r!=

35

840

=24⇒r=4

n

P

r

=

(n−r)!

n!

=840

⇒n×(n−1)×(n−2)×(n−3)=840

⇒840=4×5×6×7

⇒n=7