Question

How do you evaluate `9P4`?

Answer 1

`" "^9P_4" "=3024`

Explanation:

`" "^nP_r" "`has the formula

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

so`" "^9P_4" "=(9!)/((9-4)!)`

so`" "^9P_4" "=(9!)/(5!)=(9xx8xx7xx6xxcancel(5!))/cancel((5!)`

`" "^9P_4" "=(9!)/(5!)=9xx8xx7xx6=3024`