Table of Contents
Multiplying a 2×2 matrix by another 2×2 matrix results in a new 2×2 matrix where each element is calculated by taking the dot product of the corresponding row and column in the two matrices. The resulting matrix will have a dimension of 2×2 and will contain the sum of the products of the elements in each row and column of the original matrices. This operation is also known as matrix multiplication and is an important mathematical operation used in various fields such as engineering, physics, and computer science.
Matrix Multiplication: (2×2) by (2×2)
Suppose we have a 2×2 matrix A, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.super_short2 {
max-width: 180px;
margin: 5px auto;
color: blue;
}
A = |
|
Suppose we also have a 2×2 matrix B, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short2 {
max-width: 180px;
margin: 5px auto;
color: red;
}
B = |
|
To multiply matrix A by matrix B, we use the following formula:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.long{
max-width: 500px;
margin: 5px auto;
color: #000000;
}
.red {
color: red;
}
.blue {
color: blue;
}
A x B = |
|
This results in a 2×2 matrix.
The following examples illustrate how to multiply a 2×2 matrix with a 2×2 matrix using real numbers.
Example 1
Suppose we have a 2×2 matrix C, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.super_short {
max-width: 150px;
margin: 5px auto;
color: #000000;
}
C = |
|
Suppose we also have a 2×2 matrix D, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short {
max-width: 250px;
margin: 5px auto;
color: #000000;
}
D = |
|
Here is how to multiply matrix C by matrix D:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.medium {
max-width: 500px;
margin: 5px auto;
color: #000000;
}
.red {
color: red;
}
.blue {
color: blue;
}
C x D = |
|
This results in the following 2×2 matrix:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short {
max-width: 180;
margin: 5px auto;
color: #000000;
}
C x D = |
|
Example 2
Suppose we have a 2×2 matrix E, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.super_short {
max-width: 150px;
margin: 5px auto;
color: #000000;
}
E = |
|
Suppose we also have a 2×2 matrix F, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short {
max-width: 180px;
margin: 5px auto;
color: #000000;
}
F = |
|
Here is how to multiply matrix E by matrix F:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.medium {
max-width: 500px;
margin: 5px auto;
color: #000000;
}
.red {
color: red;
}
.blue {
color: blue;
}
E x F = |
|
This results in the following 2×2 matrix:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short {
max-width: 180;
margin: 5px auto;
color: #000000;
}
E x F = |
|
Example 3
Suppose we have a 2×2 matrix G, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.super_short {
max-width: 150px;
margin: 5px auto;
color: #000000;
}
G = |
|
Suppose we also have a 2×2 matrix H, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short {
max-width: 180px;
margin: 5px auto;
color: #000000;
}
H = |
|
Here is how to multiply matrix G by matrix H:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.medium {
max-width: 500px;
margin: 5px auto;
color: #000000;
}
.red {
color: red;
}
.blue {
color: blue;
}
G x H = |
|
This results in the following 2×2 matrix:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short {
max-width: 180px;
margin: 5px auto;
color: #000000;
}
G x H = |
|
Example 4
Suppose we have a 2×2 matrix I, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.super_short {
max-width: 150px;
margin: 5px auto;
color: #000000;
}
I = |
|
Suppose we also have a 2×2 matrix J, which has 2 rows and 2 columns:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short {
max-width: 180px;
margin: 5px auto;
color: #000000;
}
J = |
|
Here is how to multiply matrix I by matrix J:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.medium {
max-width: 500px;
margin: 5px auto;
color: #000000;
}
.red {
color: red;
}
.blue {
color: blue;
}
I x J = |
|
This results in the following 2×2 matrix:
table {
border-collapse: collapse;
border-spacing: 0;
padding: 0;
}
td.tdleft {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-left: solid 1px #000;
width: 5px;
padding: 0;
}
td.tdreg {
padding: 2px 1px;
text-align: center;
border-bottom: solid 1px #fff;
}
td.tdright {
border-top: solid 1px #000;
border-bottom: solid 1px #000;
border-right: solid 1px #000;
width: 5px;
padding: 0;
}
.short {
max-width: 180px;
margin: 5px auto;
color: #000000;
}
I x J = |
|
Matrix Calculator
The examples above illustrated how to multiply 2×2 matrices by hand. A good way to double check your work if you’re multiplying matrices by hand is to confirm your answers with a matrix calculator. While there are many matrix calculators online, the simplest one to use that I have come across is .