Anonymous
Anonymous asked in Science & MathematicsMathematics · 2 months ago

Number of permutatons help?

I haven't understood how it resolves the 2nd line (simplifying the numerator)

Update:

What's the problem with you guys?

Update 2:

I needed to know how the 3rd line is got

Attachment image

2 Answers

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  • ?
    Lv 7
    2 months ago
    Favorite Answer

    the 2nd line is just an algebraic trick to manipulate the numbers.

              (n-r)!

              ------- = 1

              (n-r)!

    You can multiply any quantity by 1 to get the same quantity.

  • ted s
    Lv 7
    2 months ago

    what is the problem ??? IT TELLS you what they did....you do know the definition of n! ..???

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