Ngày tải lên :
15/08/2013, 15:21
... 2x
3
=2.
(4. 7)
2)
x
1
− 2x
2
+3x
3
− x
4
=6,
2x
1
+3x
2
− 4x
3
+4x
4
=7,
3x
1
+ x
2
− 2x
3
− 2x
4
=9,
x
1
− 3x
2
+7x
3
+6x
4
= −7.
(4. 8)
Gia
’
i. 1)
´
Ap du
.
ng cˆong th´u
.
c (4. 4)
x
j
=
det(A
j
)
detA
,j=
1, ... 3x
4
=8,
3x
1
+2x
2
− x
3
+2x
4
=4,
2x
1
− 3x
2
+2x
3
+ x
4
= −8.
(D
S. x
1
=1,x
2
=2,x
3
= −1, x
4
= −2)
33.
x
2
− 3x
3
+4x
4
= −5,
x
1
− 2x
3
+3x
4
= 4,
3x
1
+2x
2
− 5x
4
=12,
4x
1
+3x
2
− ... x
1
=1,x
2
=2,x
3
=1,x
4
= −1)
34.
x
1
+ x
2
− x
3
+ x
4
=4,
2x
1
− x
2
+3x
3
− 2x
4
=1,
x
1
− x
3
+2x
4
=6,
3x
1
− x
2
+ x
3
− x
4
=0.
(D
S. x
1
=1,x
2
=2,x
3
=3,x
4
=4)
35.
x
1
+ x
2
+ x
3
+ x
4
=0,
x
2
+...