矩阵()是二次型<imgwidth="112"height="28"v:shapes="_x0000_i1332"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image402.png">的矩阵
①
<imgwidth="58"height="58"v:shapes="_x0000_i1333"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image404.png">
②
<imgwidth="58"height="58"v:shapes="_x0000_i1334"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image406.png">
③
<imgwidth="58"height="58"v:shapes="_x0000_i1335"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image408.png">
④
<imgwidth="58"height="58"v:shapes="_x0000_i1336"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image410.png">