山东建筑大学
第二章 矩阵及其运算
1﹑已知两个线性变换
求从变量
到变量
的线性变换。
解 由已知
EMBED Equation.3
所以有
2﹑设
求
及
.
解
EMBED Equation.3
EMBED Equation.3
EMBED Equation.3
EMBED Equation.3
EMBED Equation.3 .
3﹑计算;
⑴
解:
EMBED Equation.3
EMBED Equation.3 .
⑵
解:
EMBED Equation.3
EMBED Equation.3 。
4.设
,求
.
解
;
利用数学归纳法证明:
当
时,显然成立,假设
时成立,则
时
由数学归纳法原理知:
.
5﹑设
求
.
解 首先观察
EMBED Equation.3 ,
由此推测
(***)
用数学归纳法证明: 当
时,显然成立. 假设
时成立,则
时,
EMBED Equation.3
由数学归纳法原理知: (***)成立.
6﹑设
都是
阶对称阵,证明
是对称阵的充要条件是
.
证明: 由已知:
充分性:
EMBED Equation.3
EMBED Equation.3
EMBED Equation.3
EMBED Equation.3
即
是对称矩阵.
必要性:
EMBED Equation.3
EMBED Equation.3
EMBED Equation.3
EMBED Equation.3 .
7.设
,
,问:
(1)
吗?
(2)
吗?
(3)
吗?
解 (1)
,
. 则
(2)
EMBED Equation.3
但
EMBED Equation.3
EMBED Equation.3
故
(3)
EMBED Equation.3
EMBED Equation.3
而
EMBED Equation.3
EMBED Equation.3
故
8.举反例说明下列命
是错误的:
(1)若
,则
;
(2)若
,则
或
;
(3)若
,且
, 则
.
解 (1) 取
,
,但
(2) 取
,
,但
且
(3) 取
,
,
.
且
但
.
9﹑已知线性变换
求从变量
到变量
的线性变换。
解:
所以
即
.
10﹑求下列方阵的逆阵:
⑴
解:
,
.
.
EMBED Equation.3 .
⑵
解:
故
存在
从而
.
(3)
解: 由对角矩阵的性质知
.
11﹑解矩阵方程:
⑴
解:
EMBED Equation.3
EMBED Equation.3
⑵
解:
EMBED Equation.3 .
12、利用逆阵解线性方程组:
.
解:解、 (1) 方程组可
示为
故
从而有
.
13、设
(
为正整数),证明:
.
证明: 一方面,
另一方面,由
有
故
EMBED Equation.3
两端同时右乘
就有
.
14、设
,
, 求
.
解 由
可得
故
EMBED Equation.3
EMBED Equation.3 .
15、设
, 其中
, 求
.
解
故
所以
而
故
EMBED Equation.3 .
16.设矩阵
可逆,证明其伴随阵
也可逆,且
。
证 因
=
,由
的可逆性及
,可知
可逆,且
=
;
另一方面,由伴随阵的性质,有
=
.
用
左乘此式两边得
=
=
=
,
比较上面两个式子,即知结论成立。
17、设
阶方阵
的伴随阵为
,
证明: ⑴若
,则
; ⑵
.
证明 (1) 用反证法证明.假设
则有
.
由此得
EMBED Equation.3 .
这与
矛盾,故当
时, 有
.
(2) 由于
取行列式得到:
若
则
若
由(1)知
此时命题也成立
故有
.
18.设
,
,求
。
解 由于所给矩阵方程中含有
及其伴随矩阵
,因此仍从公式
=
着手。为此,用
左乘所给方程两边,得
,
又,
=2AB-8E
EMBED Equation.3 =8E
EMBED Equation.3 =4E.
注意到
=
=
,是可逆矩阵,且
=
,
于是
=4
=
.
19、设
,求
及
及
.
解
, 令
,
. 则
.
故
EMBED Equation.3 .
.
.
.
_1070385972.unknown
_1074161492.unknown
_1074165156.unknown
_1223228206.unknown
_1223229659.unknown
_1247216848.unknown
_1247222120.unknown
_1247232994.unknown
_1247233906.unknown
_1247222232.unknown
_1247232992.unknown
_1247216893.unknown
_1247217753.unknown
_1247216849.unknown
_1223229664.unknown
_1223229668.unknown
_1247210392.unknown
_1247213638.unknown
_1223229670.unknown
_1223229671.unknown
_1223229666.unknown
_1223229667.unknown
_1223229665.unknown
_1223229662.unknown
_1223229663.unknown
_1223229660.unknown
_1223229655.unknown
_1223229657.unknown
_1223229658.unknown
_1223229656.unknown
_1223229652.unknown
_1223229654.unknown
_1223229651.unknown
_1223227848.unknown
_1223228060.unknown
_1223228163.unknown
_1223228183.unknown
_1223228100.unknown
_1223227932.unknown
_1223227965.unknown
_1223227874.unknown
_1223227916.unknown
_1223227858.unknown
_1074167903.unknown
_1074168344.unknown
_1100085726.unknown
_1223227330.unknown
_1100086369.unknown
_1074168449.unknown
_1074168517.unknown
_1074168545.unknown
_1074168373.unknown
_1074168079.unknown
_1074168238.unknown
_1074167987.unknown
_1074165293.unknown
_1074165740.unknown
_1074165753.unknown
_1074165398.unknown
_1074165268.unknown
_1074163797.unknown
_1074164137.unknown
_1074164763.unknown
_1074164883.unknown
_1074164481.unknown
_1074163879.unknown
_1074163947.unknown
_1074163834.unknown
_1074162482.unknown
_1074163676.unknown
_1074163711.unknown
_1074162491.unknown
_1074162043.unknown
_1074162155.unknown
_1074161969.unknown
_1070386267.unknown
_1070386605.unknown
_1070386906.unknown
_1070387711.unknown
_1074161305.unknown
_1074161347.unknown
_1074161153.unknown
_1070389089.unknown
_1070387026.unknown
_1070387028.unknown
_1070387605.unknown
_1070387027.unknown
_1070386911.unknown
_1070387023.unknown
_1070387024.unknown
_1070387021.unknown
_1070387022.unknown
_1070387020.unknown
_1070386910.unknown
_1070386897.unknown
_1070386902.unknown
_1070386904.unknown
_1070386905.unknown
_1070386903.unknown
_1070386900.unknown
_1070386901.unknown
_1070386898.unknown
_1070386715.unknown
_1070386717.unknown
_1070386895.unknown
_1070386896.unknown
_1070386893.unknown
_1070386894.unknown
_1070386892.unknown
_1070386716.unknown
_1070386614.unknown
_1070386714.unknown
_1070386713.unknown
_1070386610.unknown
_1070386386.unknown
_1070386555.unknown
_1070386581.unknown
_1070386601.unknown
_1070386578.unknown
_1070386394.unknown
_1070386553.unknown
_1070386554.unknown
_1070386398.unknown
_1070386390.unknown
_1070386364.unknown
_1070386366.unknown
_1070386377.unknown
_1070386365.unknown
_1070386276.unknown
_1070386356.unknown
_1070386357.unknown
_1070386355.unknown
_1070386268.unknown
_1070386044.unknown
_1070386061.unknown
_1070386261.unknown
_1070386266.unknown
_1070386260.unknown
_1070386259.unknown
_1070386055.unknown
_1070386060.unknown
_1070386052.unknown
_1070385998.unknown
_1070386033.unknown
_1070386041.unknown
_1070386029.unknown
_1070385974.unknown
_1070385986.unknown
_1070385973.unknown
_1070385602.unknown
_1070385696.unknown
_1070385731.unknown
_1070385745.unknown
_1070385753.unknown
_1070385948.unknown
_1070385969.unknown
_1070385968.unknown
_1070385933.unknown
_1070385748.unknown
_1070385738.unknown
_1070385742.unknown
_1070385734.unknown
_1070385709.unknown
_1070385725.unknown
_1070385728.unknown
_1070385722.unknown
_1070385703.unknown
_1070385706.unknown
_1070385699.unknown
_1070385638.unknown
_1070385676.unknown
_1070385687.unknown
_1070385690.unknown
_1070385680.unknown
_1070385655.unknown
_1070385664.unknown
_1070385672.unknown
_1070385668.unknown
_1070385660.unknown
_1070385647.unknown
_1070385651.unknown
_1070385643.unknown
_1070385617.unknown
_1070385629.unknown
_1070385634.unknown
_1070385623.unknown
_1070385604.unknown
_1070385612.unknown
_1070385603.unknown
_1070385483.unknown
_1070385594.unknown
_1070385598.unknown
_1070385600.unknown
_1070385601.unknown
_1070385599.unknown
_1070385596.unknown
_1070385597.unknown
_1070385595.unknown
_1070385498.unknown
_1070385590.unknown
_1070385592.unknown
_1070385593.unknown
_1070385591.unknown
_1070385588.unknown
_1070385589.unknown
_1070385586.unknown
_1070385587.unknown
_1070385501.unknown
_1070385491.unknown
_1070385494.unknown
_1070385487.unknown
_1070385344.unknown
_1070385453.unknown
_1070385476.unknown
_1070385480.unknown
_1070385473.unknown
_1070385364.unknown
_1070385452.unknown
_1070385451.unknown
_1070385358.unknown
_1070385361.unknown
_1070385348.unknown
_1070385272.unknown
_1070385274.unknown
_1070385341.unknown
_1070385273.unknown
_1070385190.unknown
_1070385270.unknown
_1070385271.unknown
_1070385268.unknown
_1070385269.unknown
_1070385267.unknown
_1070385193.unknown
_1070385188.unknown
_1070385189.unknown
_1031750322.unknown
_1031750590.unknown
_1070385187.unknown
_1031750523.unknown
_1031750266.unknown