Explanation:
#34.
After a dilation of 2 (about the origin), all coordinates will be doubled.
Thus the image is 2 time the original matrix, or
-6 -4 -1
8 2 10
#37
a12 means the element on the first row, and the second element from the left.
The question does not indicate which matrix is named "a", but by elimination, we will assume it is the first matrix in the matrix equation.
Isolating the elements 12 (first row, second element) in the equation, we get
a12+5 = 1
which tells us that
a12=1-5 = -4