Question

(n+2)! / 3!n! = n! / (n-1)!​

Answer 1

(n+2)(n+1).n!/3!.n!= n.(n-1)! /(n-1)!

(n²+3n+2)/6=n

n²+3n+2=6n

n²+3n-6n+2=0

n²-3n+2=0

n²-n-2n+2=0

n(n-1)-2(n-1)=0

(n-1)(n-2)=0

n-1=0⇒n=1

n-2=0⇒n=2