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线性代数行列式习题+问题详解

第一章习题1-1.计算下列行列式(1)713501163.(2)4321651005311021.(3)222111ab c a b c . (4)2010411063143211111.(5)49362516362516925169416941.1-2.计算行列式abcdb a dc cd a b d c b a.1-3.计算n 阶行列式(1)n321332122211111.(2)14321432113213121321n nnn nn n n---.(3)21111121111211112------. 1-4. 证明:(1)2221112222221111112c b a c b a c b a b a a c c b b a a c c b b a a c cb =+++++++++.(2)321321321332321332321332321c c c b b b a a a c mc c lc kc c b mb b lb kb b a ma a la ka a =+++++++++.(3)222244441111a b c d a b c d a b c d ()()()()()()()b a c a d a c b d b d c a b c d =------+++.1-5.计算行列式xyy x y x y x 0000000000.1-6.计算4阶行列式112233440000000a b a b b a b a . 1-7. 如果行列式∆=nnn n nna a a a a a a a a212222111211,试用∆表示行列式nnn n n nn a a a a a a a a a a a a 11211213323122221的值. 1-8.利用克莱姆法则解线性方程组⎪⎪⎩⎪⎪⎨⎧=+-+-=+-=--=+-+067452296385243214324214321x x x x x x x x x x x x x x . 1-9. 问λ取何值时,齐次线性方程组可能有非零解?12120x x x x λλ+=⎧⎨+=⎩ 1-10.已知()413571200=10301004ij D a =,求11121314A A A A +++.第一章习题解答1-1.计算下列行列式(1)713501163(2)4321651005311021(3)2010411063143211111(4)49362516362516925169416941(5)222111a b c a b c .(1)解一 由三阶行列式定义得7135011633076531111033516170901*******.=⨯⨯+⨯⨯+⨯⨯-⨯⨯-⨯⨯-⨯⨯=++---=解二2331123361105105105361056317317018r r r r r r --↔==--23325105105018018340560034r r r r ↔-=-=-=-.(2)解213241120112011201135001510151015601560007123400330033r r r r r r -----==34120101512100330007r r ↔-==.(3)解43433232211111111111111234012301231361001360013141020014100014r r r r r r r r r r -----==4311110123100130001r r -==. (4)解43433232211491614916149164916253579357909162536579112222162536497911132222r r r r r r r r r r -----===.(5)解 222111()()()ab c c b c a b a a b c =---. 1-2.计算行列式abcdb a dc cd a b d c b a.解12341111()r r r r ab c d b a d c b a d c a b c d c d a b c d a bdcba dcba+++=+++41322110()c c c c c c b a bd a c b a b c d c d c a d b c dc db ca d------=+++------()a b d ac b a b cd d c a db c c db ca d---=+++------ 3221()000r r r r a b d a c b a b c d a b c da b c da b c d++---=+++--++--+--21()()(1)d a c b a b c d a b c d a b c da b c d+--=+++--+-+--+--[]()()()()()()()()().a b c d a b c d a b c d d a c b a b c d a b c d a b c d a b c d =-+++--++-----=+++--++---+-1-3.计算n 阶行列式(1)n321332122211111.(2)143214321132********n nn n nn n n---.(3)21111121111211112------.(1)解 1122111111111122201111123300111230001n n n n r r r r r r n------==. (2)解12123112312131113123111311(1)22341134123411341nc c c n n n n n n n n n n n n n n n n n n+++------+=2131112310100001200(1)2112001111n r r r r r r n n n n n n------+=--10001200(1)113021111n n n--+=--1(1)!(1).2n n -+=-(3)解 21111111112111021111211012111111210112n D +--+==---+-----+--, 按第一列展开成两个行列式得111111111211021111210121111112112n D -=+--------213111111032200320003n nr r r r r r n D +++-=+ 112122122333333n n n n n n n D D D -------=+=++=++++12212221333333512n n n n ----=++++=++++-12213313333111132n n n n ---+=++++++=+=-.1-4. 证明:(1)2221112222221111112c b a c b a c b a b a a c c b b a a c c b b a a c cb =+++++++++.证11111111111111112222222222222222b cc a a b b c a a b c c a a b b c c a a b b c a a b c c a a b b c c a a b b c a a b c c a a b ++++++++++=++++++++++++左= 1111111122222222b c a a c a a b b c a a c a a b b c a a c a a b ++=+++++111111222222bc a c a b b c a c a b b c a c a b =+1112222a b c a b c a b c ==右. (2)321321321332321332321332321c c c b b b a a a c mc c lc kc c b mb b lb kb b a ma a la ka a =+++++++++. 证 1323123233122312323312231232331223c lc c mc a ka la a ma a a ka a a b kb lb b mb b b kb b b c kc lc c mc c c kc c c --+++++++=+++++左=12123123123c kc a a a b b b c c c -==右. (3)222244441111a b c d abcda b c d ()()()()()()()b a c a d a c b d b d c a b c d =------+++.证 243322122224444222222222111111110=()()()0()()()r a r r ar r ar a b c d b a c a d a a b c d b b a c c a d d a a b c d b b a c c a d d a ------=------左222222222()()()()()()b ac ad a b b a c c a d d a b b a c c a d d a ---=------222111()()()()()()b ac ad a bcdb b ac c ad d a =---+++21222111()()()()()()r ar b a c a d a b ac ad ab b ac c ad d a +=---++++++23121()2222111()()()00()()()()r b r r b a r b a c a d a c bd bc b c ad b d a --+=------+-+2222()()()()()()()c bd bb ac ad a c b c a d b d a --=----+-+[]222211()()()()()()()()()()()()()()()()()()()()()()()()()()()()(b a c a d a c b d b c b c a d b d a b a c a d a c b d b d b d a c b c a b a c a d a c b d b d ad bd ab c ac bc ab b a c a d a c b d b d ad bd c ac bc b a =-----++++=-----++-++⎡⎤=-----+++----⎣⎦⎡⎤=-----++---⎣⎦=-)()()()()()()c a d a c b d b d c a b c d -----+++=右.1-5.计算行列式xyy x y x y x 0000000000.解 记000000000n x y x y D x y y x=,当1n =时,1D x =;当2n ≥时,按第1列展开得00000000000000n x y x y x y xyD x x y xyx==100000(1)0000n y x y y y xy++-1(1)n n n x y +=+-.1-6.计算4阶行列式1122334400000000a b a b b a b a . 解11222222111413313333444400000(1)0(1)000a b a b a b a b a b a b b a b a a b b a ++=-+- 2222333114143333(1)(1)a b a b a a b b b a b a ++=⨯--⨯-()()142323142323a a a a b b bb a a b b =---14142323()()a a b b a a b b =--. 1-7. 如果行列式∆=nnn n nna a a a a a a a a212222111211,试用∆表示行列式nnn n n nn a a a a a a a a a a a a 11211213323122221的值.解112212122211121313232122211121211121(1)(1)n n n n r r n r r n n r r n n n n n nn n n nnna a a a a a a a a a a a a a a a a a a a a ---↔↔↔--=-=-∆.1-8.利用克莱姆法则解线性方程组⎪⎪⎩⎪⎪⎨⎧=+-+-=+-=--=+-+067452296385243214324214321x x x x x x x x x x x x x x .解 方程组的系数行列式2151130627002121476D ---==≠--,181********52120476D ---==---,2285119061080512176D --==----,321811396270252146D --==--,4215813092702151470D --==---,方程组的解为12343,4,1,1x x x x ==-=-=.1-9. 问λ取何值时,齐次线性方程组可能有非零解?12120x x x x λλ+=⎧⎨+=⎩解 方程组的系数行列式211(1)(1)1D λλλλλ==-=+-,当1λ=或1λ=-时,0D =,方程组可能有非零解.1-10. 已知()413571200=10301004ij D a =,求11121314A A A A +++.解 1234411122341112131411111111112000200==103000301004004k c c c c k A A A A =----+++∑=-2.。

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