If $A=\begin{bmatrix}x+4,& 2\\3 & 1\end{bmatrix}, B = \begin{bmatrix} x & 2x-1\\2 & 5\end{bmatrix}$ and |AB|= 12 then, the value (s) of x is/are :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → ±4
$|A|=(x+4)-6=x-2$
$|B|=5x-2(2x-1)=x+2$
so $|AB|=12⇒|A||B|=12$
$(x-2)(x+2)=12⇒x^2-4=12$
$⇒x=±4$