JAMB - Mathematics (2014 - No. 21)
If \(\begin{vmatrix}-x & 12 \\-1 & 4 \end{vmatrix} = - 12\), find x.
-6
-2
3
6
คำอธิบาย
\(\begin{vmatrix}-x & 12 \\-1 & 4\end{vmatrix} = - 12\)
-4x - (-1)12 = -12
-4x + 12 = -12
-4x = -12 - 12
-4x = - 24
x = 6
-4x - (-1)12 = -12
-4x + 12 = -12
-4x = -12 - 12
-4x = - 24
x = 6