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Properties: 5.4 Algebraic Properties of the 2-norm of a Vector
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The 2-norm of a Vector

Let nN be a positive integer and let xRn. Then, the 2-norm xRn is given by the square root of the sum of the square of the elements.

||x||2=x12+x22++xn2=j=1nxj2

Another way to calculate the 2-norm is to take the 5.1 Inner Product Between Vectors using the following formula:

||x||2=xx

Remark. The two-norm is also known as the euclidean norm.

Remark. From this point on, the two norm will be denoted with the following notation:

||x||=||x||2

Remark. There are many other vector-norms two consider. However, we will focus on the 2-norm as it is the most important when it comes to introductory linear algebra.

Remark. In Multivariable Calculus, the 2-norm of a Vector is also known as the magnitude.