2020年 军队文职 数学2 模拟卷(7)及答案解析

军队文职数学2模拟题及答案解析C.?

?11?

?01??D.??

01?

?10??

21.【答案】B2

【解析】由??12???01??????2

?1??0?2?2???

00?1??????10?

?01?。故选B。?a11?xa12?xa13?xa14?x22.设f?x??a21?2xa22?2xa23?2xa24?2xa，则多项式f?x?可能的最高次数是31?3xa32?3xa33?3xa34?3xa41?4xa41?4xa43?4xa44?4x（）A.0B.1C.2D.322.【答案】B【解析】利用行列式的性质对f?x?进行等量变换，再进行判断易于判断。a11?xa12?xa13?xa14?xa11?xa12?xa13?xa14?xf?x??a21?2xa22?2xa23?2xa24?2xa21?2a11a22?2a12a23?2a13a24?2a14aa32?3xa33?3xa34?3x?a31?3a11a32?3a12a33?3a13a?31?3x34?3a14a41?4xa41?4xa43?4xa44?4xa41?4a11a41?4a12a43?4a13a44?4a14a11a12a13a14xxxxa21?2a11a22?2a12a23?2a13a24?2a14?a21?2a11a22?2a12a23?2a13a24?2a14a31?3a11a32?3a12a33?3a13aa31?3a11a，故34?3a1432?3a12a33?3a13a34?3a14a41?4a11a41?4a12a43?4a13a44?4a14a41?4a11a41?4a12a43?4a13a44?4a14f?x?的可能的最高次数为1次。故选B。??1

1

1

1?23.设A=?

0

1?1a?

?3a4??

，若r?A*

??1，则a?（）?2?3

519?

?

16军队文职数学2模拟题及答案解析A.1B.3C.1或3D.无法确定23.【答案】C【解析】由r?A*??1，得r?A??3

，则A?0

，即111111110?

01?1a

?1a23a4?

0100a?1

2?a

??a?1??6?2a?，得a?1或3，且此时均满足35

1

900

0

6?2a

r?A??3，故选C。17