## College Algebra (6th Edition)

$\frac{20_{{P}{_{2}}}}{2!}$ -$20_{{C}{_{2}}}$ = 0
$\frac{20_{{P}{_{2}}}}{2!}$ -$20_{{C}{_{2}}}$ = $\frac{(\frac{20!}{(20 - 2)!})}{2!}$ - $\frac{20!}{(20 - 2)!.2!}$ = $\frac{20!}{(20 - 2)!.2!}$ - $\frac{20!}{(20 - 2)!.2!}$ = 0