已知<imgwidth="136"height="84"v:shapes="_x0000_i1289"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image325.png">是正定矩阵,则()
①
<imgwidth="86"height="46"v:shapes="_x0000_i1290"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image327.png">
②
<imgwidth="74"height="46"v:shapes="_x0000_i1291"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image329.png">
③
<imgwidth="86"height="48"v:shapes="_x0000_i1292"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image331.png">
④
<imgwidth="74"height="48"v:shapes="_x0000_i1293"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image333.png">