Suppose that there is matrix $A = \begin{bmatrix} 3 & 2 \\ 2 & 0 \end{bmatrix}$. We want to figure out what $\max_{||\hat{\mathbb{x}}|| = 1}||A\hat{\mathbb{x}}||$ is with the Euclidean norm. (where $\hat{\mathbb{x}}$ is $\frac{1}{||\mathbb{x}||}\mathbb{x}$.)
Answer is stated to be 4, but I am unsure why it is.