简答题:已知二次型<img src="http://www.weimei168.com/uploads/202208/161266956564751.png" width="115" height="30" /><img src="http://www.weimei168.com/uploads/202208/161266957193611.png" width="299" height="32" /> <br /> 求：(1)二次型的矩阵； <br /> (2)用配方法化二次型为标准形、规范形．