Question

Use the formula for nPr to evaluate the following expression. 5P5

Answer 1

Answer: 120

Explanation:

The permutation of n things taken r at a time is given by expression :-

`^nP_r`

The formula to evaluate
`^nP_r` is given by :-

`^nP_r=(n!)/((n-r))`

Then ,
`^5P_5` will be :-

`^5P_5=(5!)/((5-5)!)`

Since ,
`n!=n(n-1)(n-2).......(2)(1)`

Then ,
`^5P_5=(5*4*3*2*1)/(0!)=120\ \ \ \text{Also,}0!=1`

Therefore, the value of the expression
`^5P_5=120`