Question

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

Answer 1

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