【单选题】
下列矩阵中是正定矩阵的为
①
<img title=2.png alt=2.png src=https://huaweicloudobs.ahjxjy.cn/2E080B145178AC9BC8967FE369CEE96F.png/>
②
<img title=3.png alt=3.png src=https://huaweicloudobs.ahjxjy.cn/26E3A2F475FA449B3045DA9BC7D80373.png/>
③
<img title=4.png alt=4.png src=https://huaweicloudobs.ahjxjy.cn/CBAC98B85621784032FF49E333848B11.png/>
④
<img title=5.png alt=5.png src=https://huaweicloudobs.ahjxjy.cn/D938E2337C83BB0A94D9C57BE8453611.png/>
【多选题】
对矩阵<img src=https://huaweicloudobs.ahjxjy.cn/46647B0074A0C5AEAA365FAA07488079.png title=10.png alt=10.png/>进行分块可行的有
①
<img src=https://huaweicloudobs.ahjxjy.cn/A7B6445C58210BB9734B3C8F50B0429B.png title=15.png alt=15.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/C1F11AD0A5A6E27BDEF935222DAB55C7.png title=11.png alt=11.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/7A84240603B28E1800F6848B6BB3D953.png title=13.png alt=13.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/4D13CC0CC5166EEAA196AB1AA2CC35BE.png title=14.png alt=14.png/>
【单选题】
<img src=https://huaweicloudobs.ahjxjy.cn/A1301285ED35342C624A5C268E095C89.png title=M253TJ1S}661H(BNY9U1ZKA.png alt=M253TJ1S}661H(BNY9U1ZKA.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/6809FC7611D431FFDBFBF6A5787F5495.png title=UA@5UQMBFO9}2$39((YZT39.png alt=UA@5UQMBFO9}2$39((YZT39.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/08032A61DF91CBE9A6618197F83B1761.png title=%F32KO{@7RJ47[49TMWXI9V.png alt=%F32KO{@7RJ47[49TMWXI9V.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/A2737F646341BD7F37B616CADE34FC85.png title=SSD8JHZ(WPRC$61N19{9L}8.png alt=SSD8JHZ(WPRC$61N19{9L}8.png/>