Consider the vectors
\[
a = \begin{bmatrix} 1 \\ 1 \end{bmatrix}, \quad b = \begin{bmatrix} 0 \\ 3\sqrt{2} \end{bmatrix}.
\]
For real-valued scalar variable \( x \), the value of
\[
\min_x \|a x - b\|_2 \text{ is} \quad \text{(rounded off to two decimal places)}.
\]
\( \| \cdot \|_2 \text{ denotes the Euclidean norm, i.e., for } y = \begin{bmatrix} y_1 \\ y_2 \end{bmatrix}, \quad \|y\|_2 = \sqrt{y_1^2 + y_2^2}. \)