Linear Algebra Examples

Solve Using an Inverse Matrix x+y+z=12 , 2x-3y+2z=4 , x+z=2y
x+y+z=12x+y+z=12 , 2x-3y+2z=42x3y+2z=4 , x+z=2yx+z=2y
Step 1
Find the AX=BAX=B from the system of equations.
[1112-321-21][xyz]=[1240]111232121xyz=1240
Step 2
Find the inverse of the coefficient matrix.
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Set up a matrix that is broken into two pieces of equal size. On the left side, fill in the elements of the original matrix. On the right side, fill in elements of the identity matrix. In order to find the inverse matrix, use row operations to convert the left side into the identity matrix. After this is complete, the inverse of the original matrix will be on the right side of the double matrix.
[1111002-320101-21001]111100232010121001
Perform the row operation R2=-2R1+R2R2=2R1+R2 on R2R2 (row 22) in order to convert some elements in the row to 00.
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Replace R2R2 (row 22) with the row operation R2=-2R1+R2R2=2R1+R2 in order to convert some elements in the row to the desired value 00.
[111100-2R1+R2-2R1+R2-2R1+R2-2R1+R2-2R1+R2-2R1+R21-21001]1111002R1+R22R1+R22R1+R22R1+R22R1+R22R1+R2121001
R2=-2R1+R2R2=2R1+R2
Replace R2R2 (row 22) with the actual values of the elements for the row operation R2=-2R1+R2R2=2R1+R2.
[111100(-2)(1)+2(-2)(1)-3(-2)(1)+2(-2)(1)+0(-2)(0)+1(-2)(0)+01-21001]111100(2)(1)+2(2)(1)3(2)(1)+2(2)(1)+0(2)(0)+1(2)(0)+0121001
R2=-2R1+R2R2=2R1+R2
Simplify R2R2 (row 22).
[1111000-50-2101-21001]111100050210121001
[1111000-50-2101-21001]111100050210121001
Perform the row operation R3=-1R1+R3R3=1R1+R3 on R3R3 (row 33) in order to convert some elements in the row to 00.
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Replace R3R3 (row 33) with the row operation R3=-1R1+R3R3=1R1+R3 in order to convert some elements in the row to the desired value 00.
[1111000-50-210-1R1+R3-1R1+R3-1R1+R3-1R1+R3-1R1+R3-1R1+R3]1111000502101R1+R31R1+R31R1+R31R1+R31R1+R31R1+R3
R3=-1R1+R3R3=1R1+R3
Replace R3R3 (row 33) with the actual values of the elements for the row operation R3=-1R1+R3R3=1R1+R3.
[1111000-50-210(-1)(1)+1(-1)(1)-2(-1)(1)+1(-1)(1)+0(-1)(0)+0(-1)(0)+1]111100050210(1)(1)+1(1)(1)2(1)(1)+1(1)(1)+0(1)(0)+0(1)(0)+1
R3=-1R1+R3R3=1R1+R3
Simplify R3R3 (row 33).
[1111000-50-2100-30-101]111100050210030101
[1111000-50-2100-30-101]111100050210030101
Perform the row operation R2=-15R2R2=15R2 on R2R2 (row 22) in order to convert some elements in the row to 11.
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Replace R2R2 (row 22) with the row operation R2=-15R2R2=15R2 in order to convert some elements in the row to the desired value 11.
[111100-15R2-15R2-15R2-15R2-15R2-15R20-30-101]⎢ ⎢11110015R215R215R215R215R215R2030101⎥ ⎥
R2=-15R2R2=15R2
Replace R2R2 (row 22) with the actual values of the elements for the row operation R2=-15R2R2=15R2.
[111100(-15)(0)(-15)(-5)(-15)(0)(-15)(-2)(-15)(1)(-15)(0)0-30-101]⎢ ⎢ ⎢111100(15)(0)(15)(5)(15)(0)(15)(2)(15)(1)(15)(0)030101⎥ ⎥ ⎥
R2=-15R2R2=15R2
Simplify R2R2 (row 22).
[11110001025-1500-30-101]⎢ ⎢11110001025150030101⎥ ⎥
[11110001025-1500-30-101]⎢ ⎢11110001025150030101⎥ ⎥
Perform the row operation R1=-1R2+R1R1=1R2+R1 on R1R1 (row 11) in order to convert some elements in the row to 00.
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Replace R1R1 (row 11) with the row operation R1=-1R2+R1R1=1R2+R1 in order to convert some elements in the row to the desired value 00.
[-1R2+R1-1R2+R1-1R2+R1-1R2+R1-1R2+R1-1R2+R101025-1500-30-101]⎢ ⎢1R2+R11R2+R11R2+R11R2+R11R2+R11R2+R101025150030101⎥ ⎥
R1=-1R2+R1R1=1R2+R1
Replace R1R1 (row 11) with the actual values of the elements for the row operation R1=-1R2+R1R1=1R2+R1.
[(-1)(0)+1(-1)(1)+1(-1)(0)+1(-1)(25)+1(-1)(-15)+0(-1)(0)+001025-1500-30-101]⎢ ⎢ ⎢(1)(0)+1(1)(1)+1(1)(0)+1(1)(25)+1(1)(15)+0(1)(0)+001025150030101⎥ ⎥ ⎥
R1=-1R2+R1R1=1R2+R1
Simplify R1R1 (row 11).
[1013515001025-1500-30-101]⎢ ⎢1013515001025150030101⎥ ⎥
[1013515001025-1500-30-101]⎢ ⎢1013515001025150030101⎥ ⎥
Perform the row operation R3=3R2+R3R3=3R2+R3 on R3R3 (row 33) in order to convert some elements in the row to 00.
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Replace R3R3 (row 33) with the row operation R3=3R2+R3R3=3R2+R3 in order to convert some elements in the row to the desired value 00.
[1013515001025-1503R2+R33R2+R33R2+R33R2+R33R2+R33R2+R3]⎢ ⎢10135150010251503R2+R33R2+R33R2+R33R2+R33R2+R33R2+R3⎥ ⎥
R3=3R2+R3R3=3R2+R3
Replace R3R3 (row 33) with the actual values of the elements for the row operation R3=3R2+R3R3=3R2+R3.
[1013515001025-150(3)(0)+0(3)(1)-3(3)(0)+0(3)(25)-1(3)(-15)+0(3)(0)+1]⎢ ⎢ ⎢ ⎢1013515001025150(3)(0)+0(3)(1)3(3)(0)+0(3)(25)1(3)(15)+0(3)(0)+1⎥ ⎥ ⎥ ⎥
R3=3R2+R3R3=3R2+R3
Simplify R3R3 (row 33).
[1013515001025-15000015-351]⎢ ⎢ ⎢101351500102515000015351⎥ ⎥ ⎥
[1013515001025-15000015-351]⎢ ⎢ ⎢101351500102515000015351⎥ ⎥ ⎥
Perform the row operation R3=5R3R3=5R3 on R3R3 (row 33) in order to convert some elements in the row to 11.
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Replace R3R3 (row 33) with the row operation R3=5R3R3=5R3 in order to convert some elements in the row to the desired value 11.
[1013515001025-1505R35R35R35R35R35R3]⎢ ⎢10135150010251505R35R35R35R35R35R3⎥ ⎥
R3=5R3R3=5R3
Replace R3R3 (row 33) with the actual values of the elements for the row operation R3=5R3R3=5R3.
[1013515001025-150(5)(0)(5)(0)(5)(0)(5)(15)(5)(-35)(5)(1)]⎢ ⎢ ⎢ ⎢1013515001025150(5)(0)(5)(0)(5)(0)(5)(15)(5)(35)(5)(1)⎥ ⎥ ⎥ ⎥
R3=5R3R3=5R3
Simplify R3R3 (row 33).
[1013515001025-1500001-35]⎢ ⎢1013515001025150000135⎥ ⎥
[1013515001025-1500001-35]⎢ ⎢1013515001025150000135⎥ ⎥
Perform the row operation R1=-35R3+R1R1=35R3+R1 on R1R1 (row 11) in order to convert some elements in the row to 00.
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Replace R1R1 (row 11) with the row operation R1=-35R3+R1R1=35R3+R1 in order to convert some elements in the row to the desired value 00.
[-35R3+R1-35R3+R1-35R3+R1-35R3+R1-35R3+R1-35R3+R101025-1500001-35]⎢ ⎢35R3+R135R3+R135R3+R135R3+R135R3+R135R3+R101025150000135⎥ ⎥
R1=-35R3+R1R1=35R3+R1
Replace R1R1 (row 11) with the actual values of the elements for the row operation R1=-35R3+R1R1=35R3+R1.
[(-35)(0)+1(-35)(0)+0(-35)(0)+1(-35)(1)+35(-35)(-3)+15(-35)(5)+001025-1500001-35]⎢ ⎢ ⎢(35)(0)+1(35)(0)+0(35)(0)+1(35)(1)+35(35)(3)+15(35)(5)+001025150000135⎥ ⎥ ⎥
R1=-35R3+R1R1=35R3+R1
Simplify R1R1 (row 11).
[10102-301025-1500001-35]⎢ ⎢10102301025150000135⎥ ⎥
[10102-301025-1500001-35]⎢ ⎢10102301025150000135⎥ ⎥
Perform the row operation R2=-25R3+R2R2=25R3+R2 on R2R2 (row 22) in order to convert some elements in the row to 00.
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Replace R2R2 (row 22) with the row operation R2=-25R3+R2R2=25R3+R2 in order to convert some elements in the row to the desired value 00.
[10102-3-25R3+R2-25R3+R2-25R3+R2-25R3+R2-25R3+R2-25R3+R20001-35]⎢ ⎢10102325R3+R225R3+R225R3+R225R3+R225R3+R225R3+R2000135⎥ ⎥
R2=-25R3+R2R2=25R3+R2
Replace R2R2 (row 22) with the actual values of the elements for the row operation R2=-25R3+R2R2=25R3+R2.
[10102-3(-25)(0)+0(-25)(0)+1(-25)(0)+0(-25)(1)+25(-25)(-3)-15(-25)(5)+00001-35]⎢ ⎢ ⎢101023(25)(0)+0(25)(0)+1(25)(0)+0(25)(1)+25(25)(3)15(25)(5)+0000135⎥ ⎥ ⎥
R2=-25R3+R2R2=25R3+R2
Simplify R2R2 (row 22).
[10102-301001-20001-35]101023010012000135
[10102-301001-20001-35]101023010012000135
Since the determinant of the matrix is zero, there is no inverse.
No inverse
No inverse
Step 3
Since the matrix has no inverse, it cannot be solved using the inverse matrix.
No solution
 [x2  12  π  xdx ]  x2  12  π  xdx