[tex]\left( 3 - \sqrt 5 \right) \left( 3 - \sqrt 5 \right) \\\\=\left( 3 - \sqrt 5 \right) ^2\\\\=3^2 - 2 \cdot 3 \cdot \sqrt 5 + \left( \sqrt 5 \right)^2\\\\=9-6\sqrt5 +5\\\\=14-6\sqrt 5\\\\=2(\left7-3\sqrt 5 \right)[/tex]
