How do you evaluate $9P4$ ?

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Answer 1 · 2016-12-16T16:26:46

$" "^9P_4" "=3024$

$" "^nP_r" "$ has the formula

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

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

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

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

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