Scalar Multiplication of a Matrix

Q. If $A=\left[\begin{array}{cc}0& 2\\ 3& -4\end{array}\right]$ and $kA=\left[\begin{array}{cc}0& 3a\\ 2b& 24\end{array}\right]$, then the values of k, a, b are respectively.

1. -6, -12, -18
2. -6, 4, 9
3. -6, -4, -9
4. -6, 12, 18

Q. If $A=\left[\begin{array}{cc}0& 2\\ 3& -4\end{array}\right]$ and $kA=\left[\begin{array}{cc}0& 3a\\ 2b& 24\end{array}\right]$, then the values of k, a, b are respectively.

1. -6, -12, -18
2. -6, 4, 9
3. -6, -4, -9
4. -6, 12, 18

Q.

If A = $\left[\begin{array}{ccc}1& 4& 5\\ 3& 2& 6\end{array}\right]$ then second element of second row of 3A =

___