I believe the majority of the class understands how to add and subtract matrices, but do not think some of them know how to multiply, square, and cube matrices.
To multiply two matrices, dimensions
must match. The number of columns of
the first matrix must match the number of rows in the second matrix. So a matrix dimension of 2*3 can not be
multiplied by a matrix dimension of 2*4, but a matrix dimension of a 4*6 can be
multiplied by another dimension of 6*3
because the first matrix has six rows.
So the number of rows and columns match. For the result dimension it would be 4*3 because the number of
rows in the first matrix and the number of columns in the second matrix are
combined to form the result matrix dimension:
[[2, 3], [4, 1]] * [[1, 3],
[3, 4]]=[[11, 18], [7, 16]]`
[[2, 3], [4, 1], [5, 6]]
* [[1, 3], [3, 4]`=NOT POSSIBLE, because the number of columns in the first
matrix does not match the number of rows in the second matrix.
When multiplying two
matrices, all the columns of the second matrix must multiply the first row of
the first matrix. The first number of
the first row multiplies the first number of the first column in the second
matrix. The second number of the first
row of the first matrix multiplies the second number of the first column of the
second matrix and the third and so on.
Then the second row multiplies the first column and the second column;
number by number. When a row multiplies
a column, all numbers needs to added to form one number of the end matrix:
[[2, 3], [4, 1]] * [[1, 3], [3, 4]]=
[[2*1+3*3], [2*3+3*4], [4*1+ 1*3], [4*3+1*4]=[[11,
18], [7, 16]]`
When
squaring or cubing two matrices, the process is the same as the multiplication
process. For example, [[2, 3],[2,3]`^2,
is the same as [[2, 3],[2,3]`* [[2, 3],[2,3]`.
When cubing matrices, first multiply the first two matrices, then
multiply the product of the first two matrices to the third matrix.