To find -A, we use scalar multiplication. This is where we multiply each number of a matrix by a constant. In this case, the constant is -1.
So the values of -1A are:
[-3 8] on top, and [6 -5] on bottom.
Next we add A and -A together. To do this, simply add each number to it's counterpart in the other matrix.
A + (-A) = [0 0] on top and [0 0] on bottom. Since the values of -A are the opposites to the values of A, they cancel each other out.
