Algèbre Exemples
[413144441]⎡⎢⎣413144441⎤⎥⎦
Étape 1
Étape 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 11 by its cofactor and add.
Étape 1.1.1
Consider the corresponding sign chart.
|+-+-+-+-+|∣∣
∣∣+−+−+−+−+∣∣
∣∣
Étape 1.1.2
The cofactor is the minor with the sign changed if the indices match a -− position on the sign chart.
Étape 1.1.3
The minor for a11a11 is the determinant with row 11 and column 11 deleted.
|4441|∣∣∣4441∣∣∣
Étape 1.1.4
Multiply element a11a11 by its cofactor.
4|4441|4∣∣∣4441∣∣∣
Étape 1.1.5
The minor for a12a12 is the determinant with row 11 and column 22 deleted.
|1441|∣∣∣1441∣∣∣
Étape 1.1.6
Multiply element a12a12 by its cofactor.
-1|1441|−1∣∣∣1441∣∣∣
Étape 1.1.7
The minor for a13a13 is the determinant with row 11 and column 33 deleted.
|1444|∣∣∣1444∣∣∣
Étape 1.1.8
Multiply element a13a13 by its cofactor.
3|1444|3∣∣∣1444∣∣∣
Étape 1.1.9
Add the terms together.
4|4441|-1|1441|+3|1444|4∣∣∣4441∣∣∣−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
4|4441|-1|1441|+3|1444|4∣∣∣4441∣∣∣−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
Étape 1.2
Évaluez |4441|∣∣∣4441∣∣∣.
Étape 1.2.1
Le déterminant d’une matrice 2×22×2 peut être déterminé en utilisant la formule |abcd|=ad-cb∣∣∣abcd∣∣∣=ad−cb.
4(4⋅1-4⋅4)-1|1441|+3|1444|4(4⋅1−4⋅4)−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
Étape 1.2.2
Simplifiez le déterminant.
Étape 1.2.2.1
Simplifiez chaque terme.
Étape 1.2.2.1.1
Multipliez 44 par 11.
4(4-4⋅4)-1|1441|+3|1444|4(4−4⋅4)−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
Étape 1.2.2.1.2
Multipliez -4−4 par 44.
4(4-16)-1|1441|+3|1444|4(4−16)−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
4(4-16)-1|1441|+3|1444|4(4−16)−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
Étape 1.2.2.2
Soustrayez 1616 de 44.
4⋅-12-1|1441|+3|1444|4⋅−12−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
4⋅-12-1|1441|+3|1444|4⋅−12−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
4⋅-12-1|1441|+3|1444|4⋅−12−1∣∣∣1441∣∣∣+3∣∣∣1444∣∣∣
Étape 1.3
Évaluez |1441|∣∣∣1441∣∣∣.
Étape 1.3.1
Le déterminant d’une matrice 2×22×2 peut être déterminé en utilisant la formule |abcd|=ad-cb∣∣∣abcd∣∣∣=ad−cb.
4⋅-12-1(1⋅1-4⋅4)+3|1444|4⋅−12−1(1⋅1−4⋅4)+3∣∣∣1444∣∣∣
Étape 1.3.2
Simplifiez le déterminant.
Étape 1.3.2.1
Simplifiez chaque terme.
Étape 1.3.2.1.1
Multipliez 11 par 11.
4⋅-12-1(1-4⋅4)+3|1444|4⋅−12−1(1−4⋅4)+3∣∣∣1444∣∣∣
Étape 1.3.2.1.2
Multipliez -4−4 par 44.
4⋅-12-1(1-16)+3|1444|4⋅−12−1(1−16)+3∣∣∣1444∣∣∣
4⋅-12-1(1-16)+3|1444|4⋅−12−1(1−16)+3∣∣∣1444∣∣∣
Étape 1.3.2.2
Soustrayez 1616 de 11.
4⋅-12-1⋅-15+3|1444|4⋅−12−1⋅−15+3∣∣∣1444∣∣∣
4⋅-12-1⋅-15+3|1444|4⋅−12−1⋅−15+3∣∣∣1444∣∣∣
4⋅-12-1⋅-15+3|1444|4⋅−12−1⋅−15+3∣∣∣1444∣∣∣
Étape 1.4
Évaluez |1444|∣∣∣1444∣∣∣.
Étape 1.4.1
Le déterminant d’une matrice 2×22×2 peut être déterminé en utilisant la formule |abcd|=ad-cb∣∣∣abcd∣∣∣=ad−cb.
4⋅-12-1⋅-15+3(1⋅4-4⋅4)4⋅−12−1⋅−15+3(1⋅4−4⋅4)
Étape 1.4.2
Simplifiez le déterminant.
Étape 1.4.2.1
Simplifiez chaque terme.
Étape 1.4.2.1.1
Multipliez 44 par 11.
4⋅-12-1⋅-15+3(4-4⋅4)4⋅−12−1⋅−15+3(4−4⋅4)
Étape 1.4.2.1.2
Multipliez -4−4 par 44.
4⋅-12-1⋅-15+3(4-16)4⋅−12−1⋅−15+3(4−16)
4⋅-12-1⋅-15+3(4-16)4⋅−12−1⋅−15+3(4−16)
Étape 1.4.2.2
Soustrayez 1616 de 44.
4⋅-12-1⋅-15+3⋅-124⋅−12−1⋅−15+3⋅−12
4⋅-12-1⋅-15+3⋅-124⋅−12−1⋅−15+3⋅−12
4⋅-12-1⋅-15+3⋅-124⋅−12−1⋅−15+3⋅−12
Étape 1.5
Simplifiez le déterminant.
Étape 1.5.1
Simplifiez chaque terme.
Étape 1.5.1.1
Multipliez 44 par -12−12.
-48-1⋅-15+3⋅-12−48−1⋅−15+3⋅−12
Étape 1.5.1.2
Multipliez -1−1 par -15−15.
-48+15+3⋅-12−48+15+3⋅−12
Étape 1.5.1.3
Multipliez 33 par -12−12.
-48+15-36−48+15−36
-48+15-36−48+15−36
Étape 1.5.2
Additionnez -48−48 et 1515.
-33-36−33−36
Étape 1.5.3
Soustrayez 3636 de -33−33.
-69−69
-69−69
-69−69
Étape 2
Since the determinant is non-zero, the inverse exists.
Étape 3
Set up a 3×63×6 matrix where the left half is the original matrix and the right half is its identity matrix.
[413100144010441001]⎡⎢⎣413100144010441001⎤⎥⎦
Étape 4
Étape 4.1
Multiply each element of R1R1 by 1414 to make the entry at 1,11,1 a 11.
Étape 4.1.1
Multiply each element of R1R1 by 1414 to make the entry at 1,11,1 a 11.
[441434140404144010441001]⎡⎢
⎢⎣441434140404144010441001⎤⎥
⎥⎦
Étape 4.1.2
Simplifiez R1R1.
[114341400144010441001]⎡⎢
⎢⎣114341400144010441001⎤⎥
⎥⎦
[114341400144010441001]⎡⎢
⎢⎣114341400144010441001⎤⎥
⎥⎦
Étape 4.2
Perform the row operation R2=R2-R1R2=R2−R1 to make the entry at 2,12,1 a 00.
Étape 4.2.1
Perform the row operation R2=R2-R1R2=R2−R1 to make the entry at 2,12,1 a 00.
[1143414001-14-144-340-141-00-0441001]⎡⎢
⎢⎣1143414001−14−144−340−141−00−0441001⎤⎥
⎥⎦
Étape 4.2.2
Simplifiez R2R2.
[1143414000154134-1410441001]⎡⎢
⎢⎣1143414000154134−1410441001⎤⎥
⎥⎦
[1143414000154134-1410441001]
Étape 4.3
Perform the row operation R3=R3-4R1 to make the entry at 3,1 a 0.
Étape 4.3.1
Perform the row operation R3=R3-4R1 to make the entry at 3,1 a 0.
[1143414000154134-14104-4⋅14-4(14)1-4(34)0-4(14)0-4⋅01-4⋅0]
Étape 4.3.2
Simplifiez R3.
[1143414000154134-141003-2-101]
[1143414000154134-141003-2-101]
Étape 4.4
Multiply each element of R2 by 415 to make the entry at 2,2 a 1.
Étape 4.4.1
Multiply each element of R2 by 415 to make the entry at 2,2 a 1.
[114341400415⋅0415⋅154415⋅134415(-14)415⋅1415⋅003-2-101]
Étape 4.4.2
Simplifiez R2.
[114341400011315-115415003-2-101]
[114341400011315-115415003-2-101]
Étape 4.5
Perform the row operation R3=R3-3R2 to make the entry at 3,2 a 0.
Étape 4.5.1
Perform the row operation R3=R3-3R2 to make the entry at 3,2 a 0.
[114341400011315-11541500-3⋅03-3⋅1-2-3(1315)-1-3(-115)0-3(415)1-3⋅0]
Étape 4.5.2
Simplifiez R3.
[114341400011315-115415000-235-45-451]
[114341400011315-115415000-235-45-451]
Étape 4.6
Multiply each element of R3 by -523 to make the entry at 3,3 a 1.
Étape 4.6.1
Multiply each element of R3 by -523 to make the entry at 3,3 a 1.
[114341400011315-1154150-523⋅0-523⋅0-523(-235)-523(-45)-523(-45)-523⋅1]
Étape 4.6.2
Simplifiez R3.
[114341400011315-1154150001423423-523]
[114341400011315-1154150001423423-523]
Étape 4.7
Perform the row operation R2=R2-1315R3 to make the entry at 2,3 a 0.
Étape 4.7.1
Perform the row operation R2=R2-1315R3 to make the entry at 2,3 a 0.
[1143414000-1315⋅01-1315⋅01315-1315⋅1-115-1315⋅423415-1315⋅4230-1315(-523)001423423-523]
Étape 4.7.2
Simplifiez R2.
[114341400010-5238691369001423423-523]
[114341400010-5238691369001423423-523]
Étape 4.8
Perform the row operation R1=R1-34R3 to make the entry at 1,3 a 0.
Étape 4.8.1
Perform the row operation R1=R1-34R3 to make the entry at 1,3 a 0.
[1-34⋅014-34⋅034-34⋅114-34⋅4230-34⋅4230-34(-523)010-5238691369001423423-523]
Étape 4.8.2
Simplifiez R1.
[11401192-3231592010-5238691369001423423-523]
[11401192-3231592010-5238691369001423423-523]
Étape 4.9
Perform the row operation R1=R1-14R2 to make the entry at 1,2 a 0.
Étape 4.9.1
Perform the row operation R1=R1-14R2 to make the entry at 1,2 a 0.
[1-14⋅014-14⋅10-14⋅01192-14(-523)-323-14⋅8691592-14⋅1369010-5238691369001423423-523]
Étape 4.9.2
Simplifiez R1.
[100423-1169869010-5238691369001423423-523]
[100423-1169869010-5238691369001423423-523]
[100423-1169869010-5238691369001423423-523]
Étape 5
The right half of the reduced row echelon form is the inverse.
[423-1169869-5238691369423423-523]