第一章 行 列 式
一、判断题
1.行列式如果有两列元素对应成比例,则行列式等于零. ( T ) .
2132102. 124??121.( F )(简单的性质)
01234213434.( T )(运算值相等) 3. 121??420426. n阶行列式Dn中元素aij的代数余子式Aij为n?1阶行列式. ( T )
3121437. 245?328.( F )
836256a118. a21a31a12a22a32a13a11a23 r1?2r2 2a21?a11a33a31a122a22?a12a32a132a23?a13 ( F ) a339.如果齐次线性方程组有非零解,则它的系数行列式必等于零. ( T )
10. 如果方程个数与未知数个数相等,且系数行列式不为零,则方程组一定有解. ( T ) 二、选择题()
1.若a1ra25a32a4sa53是5阶行列式中带正号的一项,则r,s的值为( B 因为是5阶所以r+s=5并且逆序数为偶).
A.r?1,s?1 B.r?1,s?4
C.r?4,s?1 D.r?4,s?4
2.下列排列是偶排列的是( 逆序数是偶数 )
A. 4312 B. 51432 C. 45312 D. 654321
2?103.若行列式1x?2?0, 则x=( 有一列或行相同则为零 ).
3?12A.–2 B. 2 C. -1 D. 1
6.设行列式
a1a2b1b2=1,
a1a2c1c2=2,则
a1a2b1?c1b2?c2=( D ).
A.-3 B.-1 C.1 D.3
?ax1?2x2?3x3?8?7.设非齐次线性方程组?2ax1?2x2?3x3?10有唯一解(系数行列式不为0),则a,b必须满
?x?x?bx?523?1足( d ).
A.a?0,b?0 B.a?2233,b?0 C.a?,b? D.a?0,b? 332228. 11253?12??1523?2503?22102是按( B )展开的.
0A.第2列 B.第2行 C.第1列 D.第1行
a119.设D?ai1a12ai2an2a1nain则下式中( B 一种字母i 或j是之和,,有两种是和为零 )annan1是正确的.
A.ai1Ai1?ai2Ai2?C.ai1A1i?ai2A2i?三、填空题
?ainAin?0 B.a1iA1j?a2iA2j??aniAnj?0
?aniAnj
?ainAni?D D.D?a1iA1j?a2iA2j?2. 四阶行列式中的一项a14a32a23a41应取的符号是___正____. 8.非零元素只有n?1行的n阶行列式的值等于____0_____.
a19. b1c110.
a2b2c2a3c1b3?8,则?2b1c3a1c2?2b2a2c3?2b3?_____16___.(因为1和3 行对调了) a3n阶行列式Dn中元素aij的代数余子式Aij与余子式Mij之间的关系是
Aij?___(?1)i?jMij_,Dn按第j列展开的Dn?__a1jA1j?a2jA2j??anjAnj
23(2)15
1?120423611? (步骤很重要)(再复杂的也这样转换) 2223 解 151?12042361c4?c221?????321251?12042360r4?r222?????310221?121423402 00r4?r123 ?????101?120423002?0? 00
ax?byay?bzaz?bxxyz(2)ay?bzaz?bxax?by?(a3?b3)yzx(;ab系数提出来--从左到az?bxax?byay?bzzxy右) 证明
ax?byay?bzaz?bx ay?bzaz?bxax?by
az?bxax?byay?bzxay?bzaz?bxyay?bzaz?bx ?ayaz?bxax?by?bzaz?bxax?by
zax?byay?bzxax?byay?bzxay?bzzyzaz?bx ?a2yaz?bxx?b2zxax?by
zax?byyxyay?bzxyzyzx ?a3yzx?b3zxy
zxyxyzxyzxyz ?a3yzx?b3yzx
zxyzxyxyz ?(a3?b3)yzx?
zxya22b (3)2cd2
(a?1)2(b?1)2(c?1)2(d?1)2(a?2)2(b?2)2(c?2)2(d?2)2(a?3)2(b?3)22?0;(展开列列想减) (c?3)(d?3)2 证明
a22b 2cd2(a?1)2(b?1)2(c?1)2(d?1)2(a?2)2(b?2)2(c?2)2(d?2)2(a?3)2(b?3)2(c?c? c?c? c?c得) (c?3)2433221(d?3)2a22b ?c2d2a22b ?c2d2
2a?12b?12c?12d?12a?12b?12c?12d?12a?32b?32c?32d?322222a?52b?5(c?c? c?c得) 2c?543322d?522?0? 22六.用克拉默法则解方程(先求系数矩阵D的值,再求D1,D2...... )
?x1?x2?x3?x4?5?1?5x1?6x2?x?2x?x?4x??2?x?5x?6x?0?1234123?1. ?; 2.?x2?5x3?6x4?02x?3x?x?5x??2?234?1?x3?5x4?6x5?0???3x1?x2?2x3?11x4?0??
.
x4?5x5?1?(1??)x1?2x2?4x3?0?七. 问?取何值时? 齐次线性方程组?2x1?(3??)x2?x3?0有非零解(系数行列式必为
?x?x?(1??)x?03?12零)?
第二章 矩 阵
一、判断题
1.若A是2?3矩阵,B是3?2矩阵,则AB是2?2矩阵. ( T ) 2.若AB?O,且A?O,则B?O.( F )
?10??12??12??10?X?3. ?的解X?????. ( F 逆矩阵在左边则T) ???2534?????34??25?4.若A是n阶对称矩阵,则A也是n阶对称矩阵. ( T )
2?15. n阶矩阵A为零矩阵的充分必要条件是A?0. ( F ) 6. 若A,B为同阶可逆矩阵,则(kA)?1?kA?1. ( F )
?420??420?????7. ?6912??6?232?. ( F )
?1?10??1?10?????8. n阶矩阵A为逆矩阵的充分必要条件是
A?0. ( T )
9.设A,B为同阶方阵,则 A?B?A?B. ( F )
?A?1?AO?10.设 A,B为n阶可逆矩阵,则 ????OB???O二、选择题
?1O? .( T ) ?1?B?1. 若A,B为n阶矩阵,则下式中( D )是正确的.
A.(A?B)(A?B)?A2?B2 B.A(B?C)?O,且A?O,必有B=C. B.(A+B)2?A2+2AB+B2 D.AB?AB 2.若As?n,Bn?l,则下列运算有意义的是( A ).
A.BTAT B.BA C.A+B D.A+BT
3.若Am?n,Bs?t,做乘积AB则必须满足( C ).
A.m=t B.m=s C.n=s D.n=t
5.设2阶矩阵A???ab?*?,则A?( A )
?cd?b??d?c??? D.??ba?? ?a?????d?b???dc???d????A.? B. C.??ca??b?a??c??????33?6. 矩阵???10??的逆矩阵是( C )
???0?0?1??0?3??A.??33?? B.??13?? C.?1?????31???1?? ? D.?13?1???10??
???
-1?37?7. 设2阶方阵A可逆,且A=??1?2?,则A=( 因为6-7=-1 ).
???27??27??2?7??37?A.??1?3? B.?13? C.??13? D.?12?
????????8. n阶矩阵A行列式为
A,则kA的行列式为( B ).