3 in one question

questions A-C in question 1

Use the factorial formula for combinations to prove that in general, nCr=nCnr. What is the factorial formula for combinations? A. nCr=(nr)!n! B. nCr=r!(nr)!n! C. nCr=n!(nr)!r! D. nCr=(nr)!r! Using this formula, what is the formula for nCnr ? A. nCnr=(nr)!(n(nr))!(nr)! B. nCnr=n!(nr)!(nr)! C. nCnr=(nr)!(r(nr))!n! What is the simplified result? A. nCnr=r!n!(nr)! B. nCnr=r!(nr)!n! C. nCnr=((nr)!)2n! D. nCnr=(r!)2n!