Question

    If (1×2×3×4×.....n) = n!,

    then [(14)! - (13)! - (12)!] is equal to:

    A 14 × 12 × (12)! Correct Answer Incorrect Answer
    B 14 × 12 × (13)! Correct Answer Incorrect Answer
    C 14 × (13) × (13)! Correct Answer Incorrect Answer
    D 13 × 12 × (12)! Correct Answer Incorrect Answer

    Solution

    (14!-13!-12!) =14×13×12! - 13×12! - 12! = 12! [14×13-13-1] = 12! [14×13 - 14] = 12! ×14 [13-1] = 12!×14×12

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