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16 votes
16 votes
Find the indicated expression, where n = 7, r = 5. (Simplify the answer as much as possible.)n!/(n-r)!r!

User Danizmax
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1 Answer

11 votes
11 votes

Given:

n = 7, r =5

We are required to evaluate the expression:


(n!)/((n-r)!r!)

Substituting we have:


=\text{ }(7!)/((7-5)!5!)

Now let's simplify:


\begin{gathered} =\text{ }(7*6*5!)/(2!*5!) \\ =\text{ 7 }*\text{ 3} \\ =\text{ 21} \end{gathered}

Answer: 21

User Roehrijn
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