CUET Preparation Today
If A and B are square matrices of order 3 such that $|A|= 3$ and $|B|=-1$, then $|3AB|$ is equal to |
-9 -81 -3 -27 |
-81 |
The correct answer is Option (2) → -81 Given $|A|=3,\;|B|=-1$ Order of matrices is $3\times3$. Use property: $|kA|=k^{n}|A|$ for an $n\times n$ matrix. So $|3AB|=3^{3}|AB|$ Also $|AB|=|A||B|$ Thus $|3AB|=27\cdot3\cdot(-1)$ $=-81$ |
