(3-a) ²- √0.2 · √180a ² jup mk voi

\[\begin{array}{l} {\left( {3 - a} \right)^2} - \sqrt {0,2} .\sqrt {180{a^2}} \\ = 9 - 6a + {a^2} - \sqrt {0,2.180{a^2}} \\ = 9 - 6a + {a^2} - \sqrt {36{a^2}} \\ = 9 - 6a + {a^2} - 6\left| a \right|\\ = \left[ \begin{array}{l} 9 - 6a + {a^2} - 6a\,\,\,\,khi\,\,\,a \ge 0\\ 9 - 6a + {a^2} + 6a\,\,\,\,khi\,\,\,a < 0 \end{array} \right.\\ = \left[ \begin{array}{l} 9 - 12a + {a^2}\,\,\,\,khi\,\,\,a \ge 0\\ 9 + {a^2}\,\,\,\,\,\,khi\,\,\,a < 0 \end{array} \right.. \end{array}\]