Jambmaths question:
If $^{n}{{P}_{3}}-6{{(}^{n}}{{C}_{4}})=0,$ find the value of n
Option A:
5
Option B:
6
Option C:
7
Option D:
8
Jamb Maths Solution:
$\begin{align} & ^{n}{{P}_{3}}-6{{(}^{n}}{{C}_{4}})=0 \\ & ^{n}{{P}_{3}}=6{{(}^{n}}{{C}_{4}}) \\ & \frac{n!}{(n-3)!}=\frac{6n!}{4!(n-4)!} \\ & \frac{n!}{(n-3)(n-4)!}=\frac{6n!}{24(n-4)!} \\ & 24=6(n-3) \\ & 4=n-3 \\ & n=7 \\\end{align}$
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