Answer
(a.) Size $=4\times 3$.
(b.) Element $=-3$.
Work Step by Step
(a.)
The size of the matrix is equal to number of rows multiply by number of columns.
The given matrix is
$\begin{bmatrix}
1& -2&6\\
0 & -3& 2 \\
0& 1 & 1 \\
-3&2&5
\end{bmatrix}$
Number of rows $=4$.
and number of columns $=3$.
Hence, the size of the matrix is $4\times 3$.
(b.)
$(4,1)$ is a position at row $4$, column $1$.
The element at row $4$, column $1$ is $-3$.
Hence, the element is $-3$.
