填空题:设二次型<img src="http://www.weimei168.com/uploads/202208/161258116598161.png" width="20" height="27" />(<img src="http://www.weimei168.com/uploads/202208/161258117158951.png" width="70" height="30" />)=<img src="http://www.weimei168.com/uploads/202208/16125811778691.png" width="204" height="32" />，则二次型的对应矩阵是_______．