Algebra and Trigonometry 10th Edition

Published by Cengage Learning
ISBN 10: 9781337271172
ISBN 13: 978-1-33727-117-2

Chapter 11 - 11.6 - Counting Principles - 11.6 Exercises - Page 825: 87


The identity is verified. $_nP_{n-1}=~_nP_n$

Work Step by Step

$_nP_{n-1}=\frac{n!}{[(n-(n-1)]!}=\frac{n!}{1!}$ But, $1!=1=0!$ $_nP_{n-1}=\frac{n!}{1!}=\frac{n!}{0!}=\frac{n!}{(n-n)!}=~_nP_n$
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