\(\begin{array}{l}2\sqrt 2 + \sqrt {18} - \sqrt {32} = 2\sqrt 2 + 3\sqrt 2 - 4\sqrt 2 \\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \left( {2 + 3 - 4} \right)\sqrt 2 \\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \,\,\,\,\,\sqrt 2 \end{array}\)