Question

How do you find the value of the permutation P(4,2)?

Answer 1

`12`

Explanation:

`"using the definition"`

`•color(white)(x)^nP_r=(n!)/((n-r)!)`

`"where "n! =n(n-1)(n-2)xx... xx3xx2xx1`

`color(white)(x)^4P_2=(4!)/((4-2)!)=(4!)/(2!)`

`color(white)(xxxxxxxxxx)=(4xx3xxcancel(color(red)(2xx1)))/cancel(color(red)(2xx1))=4xx3=12`