Reveiw matricies

When multiplying matrices (a)(b)x(b)(c) the inner numbers have to match, and the resulting matrix will be a(c)

Example 1:
Find each matrix product, if it is defined.
[-6 [-1 12 = Not Defined
0] 0 -4]
2x1 2x2
The inner numbers do not match, so it is not defined.

Example 2:
Find each matrix product, if it is defined.
[-2 3 [0 3 = [-18 9
4 2] -6 5] -12 32]
2x2 2x2
-2(0)+3(-6)=-18
-2(3)+3(5)=9
4(0)+2(-6)=-12
4(3)+4(5)=32
Exapmle 3:
Find each matrix product, if it is defined.
[8 -10 [-2 = Not Defined
0 3 -9
-6 4] 1]
3x2 3x1
The inner number do not match, so it is not defined.