Prove that (" my Enfor alintegers n 21. . . . To prove the identity, first prove n. Start with the left side of the equation and solve for the right side. n! 1 = 1!(n - 1)! Apply the combination counting formula. n(n - 1)! = 1 (n - 1)! Use the basic factorial identities. = n Divide out the common factor. Use Pascal's triangle. Use the basic factorial identities