Jambmaths question:
If $N=\left( \begin{matrix} 3 & 5 & -4 \\ 6 & -3 & -5 \\ -2 & 2 & 1 \\\end{matrix} \right)$, find $\left| N \right|$
Option A:
17
Option B:
23
Option C:
65
Option D:
91
Jamb Maths Solution:
$\begin{align} & \left| N \right|=\left| \begin{matrix} 3 & 5 & -4 \\ 6 & -3 & -5 \\ -2 & 2 & 1 \\\end{matrix} \right| \\ & \left| N \right|=3\left| \begin{matrix} -3 & -5 \\ 2 & 1 \\\end{matrix} \right|-5\left| \begin{matrix} 6 & -5 \\ -2 & 1 \\\end{matrix} \right|-4\left| \begin{matrix} 6 & -2 \\ 2 & 2 \\\end{matrix} \right| \\ & =3(-3+10)-5(6-10)-4(12-6) \\ & =21+20-24 \\ & =17 \end{align}$
Jamb Maths Topic:
Year of Exam: