1.
m n :
. (1)
x 1, x 2, ¼, xn , aij (i = 1,2, ¼, m;
j = 1, 2, ¼, n) , ( , ), b 1, b 2, ¼, bm , .
x 1, x 2, ¼, xn, .
, .
, , .
, . , , ( ).
, .
,
(b 1 = b 2 =¼ = bn = 0), . , n .
(m=n), .
, , ( , , ).
.
, , , . : , , - .
. (1)
a 11 . , , , , x 1 .
:
1) a 11¹0, ;
2) , , , 4;
3) , 3;
4) , 5.
, , x 1 ( 1 4):
. (2)
, , , , .
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, .
. (3)
, p q , p ´ q:
.
aij . , , . p = q, , . aii .
(3) . , , .
, .
m n , m n +1 . . (2)
.
:
1) , a 22 ;
2) ;
3) 5 .
, , x 1 , , x 2 :
.
x 3 . :
1) , a 33 ¹ 0;
2) , 39, :
.
. (4)
x 4 = 2. , x 3 = 3. , x 2 = 1, x 1 = 1. , ( x 4, x 3 . .).
:
1) ;
2) , ;
3) , .
A , A B, , .
, , , , . (4) .
, .
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:
. (5)
:
1) ;
2) ;
3) ;
4) ;
5) .
.
, :
.
, , , x 3 , 5 2
.
0 x 1+0 x 2+0 x 3+0 x 4+0 x 5 = 0. x 1, x 2, ¼, x 5, . ,
. (6)
x 3 2 x 4 + 3 x 5 = 4. x 4 x 5 : x 4 = r; x 5 = s, , (6), x 3 = 4 + 2 r 3 s. x 3, x 4, x 5 , x 2 = 3 + 2 r 2 s. x 1 = 4 r + s.
.
A, m , n. A : m , A . , (6) .
0 x 1 + 0 x 2 + ¼0 xn = bj (bj ¹ 0),
, x 1, x 2, ¼, xn .
, , .
, r s.
, ( , ), . x 1, x 2, x 3. . x 4, x 5. , .
.
, .
, , .
, .
, .
. , , 3- 4- (6). x 1, x 2, x 4, x 3 x 5. , x 1 x 2, x 3, x 4, x 5.
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, , .
, :
.
:
.
, , , :
.
. x 3, x 5 x 1, x 2, x 4. :
.
:
.
:
.
0 x 1 + 0 x 2 + 0 x 3 = 1. , .
. , a 11 ( , x 1 ), : , x 1 .
,
, ( , ), , , , x 2.
, x 3.
, :
1) , , ;
2) , ;
3) ( 1), .
A p ´ q :
.
:
A = (aij); i = 1, 2, 3, ¼, p; j = 1, 2, 3, ¼, q.
p ´ q , ( i -
j- ; i =1, 2,..., p; j =1, 2,..., q).
A = (aij) a , a A = (aaij), A a , A, a.
A B A = (aij), B = (bij), A + B C = (cij) , cij = aij + bij, .
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A B, C = AB, n A B, C , A , B. C
.
cij - C i-