Multiplication of two matrices is possible if the number of columns in
\the first matrix equals the number of rows in the second matrix.
\ \Let A be the first matrix and B be the second matrix.
\The dimensions of the first matrix A are
, so the number of the
columns in the first matrix is 1.
\The dimensions of the second matrix B are
, so the number of the
rows in the second matrix B is 1.
\The number of columns in the first matrix equals the number of rows
\in the second matrix. So, matrix product is possible and
\its dimensions are
.
Let P be the matrix product.
\
The matrix P is
\
The element
of the matrix (
) is the sum of the products
of the corresponding elements in the i th row of the
\first matrix (
) and column j th column of the second matrix (
).
where
is the row index and
Find the element
.
The element
is the sum of the products of the corresponding
elements of row 1 of the matrix A and column 1 of the second matrix.
\
.

Next find the element
.
The element
is the sum of the products of the corresponding
elements of row 1 of the matrix A and column 2 of the second matrix.
\
.

Next find the element
.
The element
is the sum of the products of the corresponding
elements of row 1 of the matrix A and column3 of the second matrix.
\
.

Next find the element
.
The element
is the sum of the products of the corresponding
elements of row 2 of the matrix A and column 1 of the second matrix.
\
.

Next find the element
.
The element
is the sum of the products of the corresponding
elements of row 2 of the matrix A and column 2 of the second matrix.
\
.

Next find the element
.
The element
is the sum of the products of the corresponding
elements of row 2 of the matrix A and column 3 of the second matrix.
\
.

Simplify the product matrix.
\
The product matrix is 