Prove that : n! (n+2) = n! + (n+1)!
LHS = n! (n+2) = n! + (n+1)! = n! (n+1)! = n! + (n+1)(n+1-1)! = n! + (n+1)! = n! + (1+n+1) = n! (n+2) =LHS ∴ n! (n+2) = n! + (n+1)! Hence, proved.