Tính: a) \(\sqrt {12} .\left( {\sqrt {12} + \sqrt 3 } \right);\) b) \(\sqrt 8 .\left( {\sqrt {50} - \sqrt 2 } \right);\) c) \[{\left( {\sqrt 3 + \sqrt 2 } \right)^2} - 2\sqrt 6 .\]