Question

`n_(P_(5))=42.n_(P_(3)) find n?​

Answer 1

Answer:

11

Step-by-step explanation:

nP5​​=42 nP3​​

((n−5)!n!​)=42((n−3)!n!​)

⇒(n−4)(n−5)=42

⇒n2−9n−22=0

⇒n=−2;11

As n should be positive

⇒n=11