实二次型<imgwidth="270"height="26"v:shapes="_x0000_i1342"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image422.png">,则负惯性指数为()
①
<imgwidth="14"height="20"v:shapes="_x0000_i1343"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image318.png">
②
<imgwidth="10"height="18"v:shapes="_x0000_i1344"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image323.png">
③
<imgwidth="14"height="18"v:shapes="_x0000_i1345"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image426.png">
④
<imgwidth="14"height="20"v:shapes="_x0000_i1346"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds05.files/image428.png">