Đại số Ví dụ
[314121010]⎡⎢⎣314121010⎤⎥⎦
Bước 1
Bước 1.1
Choose the row or column with the most 00 elements. If there are no 00 elements choose any row or column. Multiply every element in row 33 by its cofactor and add.
Bước 1.1.1
Consider the corresponding sign chart.
|+-+-+-+-+|∣∣
∣∣+−+−+−+−+∣∣
∣∣
Bước 1.1.2
The cofactor is the minor with the sign changed if the indices match a -− position on the sign chart.
Bước 1.1.3
The minor for a31a31 is the determinant with row 33 and column 11 deleted.
|1421|∣∣∣1421∣∣∣
Bước 1.1.4
Multiply element a31a31 by its cofactor.
0|1421|0∣∣∣1421∣∣∣
Bước 1.1.5
The minor for a32a32 is the determinant with row 33 and column 22 deleted.
|3411|∣∣∣3411∣∣∣
Bước 1.1.6
Multiply element a32a32 by its cofactor.
-1|3411|−1∣∣∣3411∣∣∣
Bước 1.1.7
The minor for a33a33 is the determinant with row 33 and column 33 deleted.
|3112|∣∣∣3112∣∣∣
Bước 1.1.8
Multiply element a33a33 by its cofactor.
0|3112|0∣∣∣3112∣∣∣
Bước 1.1.9
Add the terms together.
0|1421|-1|3411|+0|3112|0∣∣∣1421∣∣∣−1∣∣∣3411∣∣∣+0∣∣∣3112∣∣∣
0|1421|-1|3411|+0|3112|0∣∣∣1421∣∣∣−1∣∣∣3411∣∣∣+0∣∣∣3112∣∣∣
Bước 1.2
Nhân 00 với |1421|∣∣∣1421∣∣∣.
0-1|3411|+0|3112|0−1∣∣∣3411∣∣∣+0∣∣∣3112∣∣∣
Bước 1.3
Nhân 00 với |3112|∣∣∣3112∣∣∣.
0-1|3411|+00−1∣∣∣3411∣∣∣+0
Bước 1.4
Tính |3411|∣∣∣3411∣∣∣.
Bước 1.4.1
Có thể tìm được định thức của một 2×22×2 ma trận bằng công thức |abcd|=ad-cb∣∣∣abcd∣∣∣=ad−cb.
0-1(3⋅1-1⋅4)+00−1(3⋅1−1⋅4)+0
Bước 1.4.2
Rút gọn định thức.
Bước 1.4.2.1
Rút gọn mỗi số hạng.
Bước 1.4.2.1.1
Nhân 33 với 11.
0-1(3-1⋅4)+00−1(3−1⋅4)+0
Bước 1.4.2.1.2
Nhân -1−1 với 44.
0-1(3-4)+00−1(3−4)+0
0-1(3-4)+00−1(3−4)+0
Bước 1.4.2.2
Trừ 44 khỏi 33.
0-1⋅-1+00−1⋅−1+0
0-1⋅-1+00−1⋅−1+0
0-1⋅-1+00−1⋅−1+0
Bước 1.5
Rút gọn định thức.
Bước 1.5.1
Nhân -1−1 với -1−1.
0+1+00+1+0
Bước 1.5.2
Cộng 00 và 11.
1+01+0
Bước 1.5.3
Cộng 11 và 00.
11
11
11
Bước 2
Since the determinant is non-zero, the inverse exists.
Bước 3
Set up a 3×63×6 matrix where the left half is the original matrix and the right half is its identity matrix.
[314100121010010001]⎡⎢⎣314100121010010001⎤⎥⎦
Bước 4
Bước 4.1
Multiply each element of R1R1 by 1313 to make the entry at 1,11,1 a 11.
Bước 4.1.1
Multiply each element of R1R1 by 1313 to make the entry at 1,11,1 a 11.
[331343130303121010010001]⎡⎢
⎢⎣331343130303121010010001⎤⎥
⎥⎦
Bước 4.1.2
Rút gọn R1R1.
[113431300121010010001]⎡⎢
⎢⎣113431300121010010001⎤⎥
⎥⎦
[113431300121010010001]⎡⎢
⎢⎣113431300121010010001⎤⎥
⎥⎦
Bước 4.2
Perform the row operation R2=R2-R1R2=R2−R1 to make the entry at 2,12,1 a 00.
Bước 4.2.1
Perform the row operation R2=R2-R1R2=R2−R1 to make the entry at 2,12,1 a 00.
[1134313001-12-131-430-131-00-0010001]⎡⎢
⎢⎣1134313001−12−131−430−131−00−0010001⎤⎥
⎥⎦
Bước 4.2.2
Rút gọn R2R2.
[113431300053-13-1310010001]⎡⎢
⎢⎣113431300053−13−1310010001⎤⎥
⎥⎦
[113431300053-13-1310010001]⎡⎢
⎢⎣113431300053−13−1310010001⎤⎥
⎥⎦
Bước 4.3
Multiply each element of R2R2 by 3535 to make the entry at 2,22,2 a 11.
Bước 4.3.1
Multiply each element of R2R2 by 3535 to make the entry at 2,22,2 a 11.
[11343130035⋅035⋅5335(-13)35(-13)35⋅135⋅0010001]⎡⎢
⎢
⎢⎣11343130035⋅035⋅5335(−13)35(−13)35⋅135⋅0010001⎤⎥
⎥
⎥⎦
Bước 4.3.2
Rút gọn R2R2.
[11343130001-15-15350010001]⎡⎢
⎢⎣11343130001−15−15350010001⎤⎥
⎥⎦
[11343130001-15-15350010001]⎡⎢
⎢⎣11343130001−15−15350010001⎤⎥
⎥⎦
Bước 4.4
Perform the row operation R3=R3-R2R3=R3−R2 to make the entry at 3,23,2 a 00.
Bước 4.4.1
Perform the row operation R3=R3-R2R3=R3−R2 to make the entry at 3,23,2 a 00.
[11343130001-15-153500-01-10+150+150-351-0]⎡⎢
⎢
⎢⎣11343130001−15−153500−01−10+150+150−351−0⎤⎥
⎥
⎥⎦
Bước 4.4.2
Rút gọn R3R3.
[11343130001-15-15350001515-351]⎡⎢
⎢
⎢⎣11343130001−15−15350001515−351⎤⎥
⎥
⎥⎦
[11343130001-15-15350001515-351]⎡⎢
⎢
⎢⎣11343130001−15−15350001515−351⎤⎥
⎥
⎥⎦
Bước 4.5
Multiply each element of R3R3 by 55 to make the entry at 3,33,3 a 11.
Bước 4.5.1
Multiply each element of R3R3 by 55 to make the entry at 3,33,3 a 11.
[11343130001-15-153505⋅05⋅05(15)5(15)5(-35)5⋅1]⎡⎢
⎢
⎢
⎢⎣11343130001−15−153505⋅05⋅05(15)5(15)5(−35)5⋅1⎤⎥
⎥
⎥
⎥⎦
Bước 4.5.2
Rút gọn R3R3.
[11343130001-15-153500011-35]⎡⎢
⎢⎣11343130001−15−153500011−35⎤⎥
⎥⎦
[11343130001-15-153500011-35]⎡⎢
⎢⎣11343130001−15−153500011−35⎤⎥
⎥⎦
Bước 4.6
Perform the row operation R2=R2+15R3R2=R2+15R3 to make the entry at 2,32,3 a 0.
Bước 4.6.1
Perform the row operation R2=R2+15R3 to make the entry at 2,3 a 0.
[1134313000+15⋅01+15⋅0-15+15⋅1-15+15⋅135+15⋅-30+15⋅50011-35]
Bước 4.6.2
Rút gọn R2.
[1134313000100010011-35]
[1134313000100010011-35]
Bước 4.7
Perform the row operation R1=R1-43R3 to make the entry at 1,3 a 0.
Bước 4.7.1
Perform the row operation R1=R1-43R3 to make the entry at 1,3 a 0.
[1-43⋅013-43⋅043-43⋅113-43⋅10-43⋅-30-43⋅50100010011-35]
Bước 4.7.2
Rút gọn R1.
[1130-14-2030100010011-35]
[1130-14-2030100010011-35]
Bước 4.8
Perform the row operation R1=R1-13R2 to make the entry at 1,2 a 0.
Bước 4.8.1
Perform the row operation R1=R1-13R2 to make the entry at 1,2 a 0.
[1-13⋅013-13⋅10-13⋅0-1-13⋅04-13⋅0-203-13⋅10100010011-35]
Bước 4.8.2
Rút gọn R1.
[100-14-70100010011-35]
[100-14-70100010011-35]
[100-14-70100010011-35]
Bước 5
The right half of the reduced row echelon form is the inverse.
[-14-70011-35]