Jambmaths question:
If $\left| \begin{matrix} 2 & -4 \\ x & 9 \\\end{matrix} \right|=58$ , find the value of x
Option A:
10
Option B:
30
Option C:
14
Option D:
28
Jamb Maths Solution:
$\begin{align} & \left| \begin{matrix} 2 & -4 \\ x & 9 \\\end{matrix} \right|=58 \\ & 18+4x=58 \\ & 4x=40 \\ & x=10 \\\end{align}$
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