Reduced row echelon form: Difference between revisions
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Solution. The corresponding augmented matrix is<br>
3 1 −4 −1<br>
1 0 10 5▼
4 1 6 1▼
▲ 1 0 10 5<br>
Create the first leading one by interchanging rows 1 and 2▼
1 0 01 5▼
3 1 −4 −1▼
4 1 6 1▼
▲ 4 1 6 1<br>
Now subtract 3 times row 1 from row 2, and subtract 4 times row 1 from row 3. The result is▼
1 0 10 5▼
0 1 −34 −16▼
0 1 −34 −19▼
Now subtract row 2 from row 3 to obtain▼
1 0 10 5▼
0 1 −34 −16▼
0 0 0 −3▼
▲Create the first leading one by interchanging rows 1 and 2<br>
This means that the following reduced system of equations▼
x + 10z = 5▼
y − 34z = −16▼
0 +0 +0 = −3▼
▲ 1 0 01 5<br>
is equivalent to the original system. In other words, the two have the same solutions. ▼
But this last system clearly has no solution (the last equation requires that x, y and z satisfy 0x+0y+0z = −3,▼
▲ 3 1 −4 −1<br>
and no such numbers exist). ▼
Hence the original system has no solution.▼
▲ 4 1 6 1<br>
▲Now subtract 3 times row 1 from row 2, and subtract 4 times row 1 from row 3. The result is<br>
▲ 1 0 10 5<br>
▲ 0 1 −34 −16<br>
▲ 0 1 −34 −19<br>
▲Now subtract row 2 from row 3 to obtain<br>
▲ 1 0 10 5<br>
▲ 0 1 −34 −16<br>
▲ 0 0 0 −3<br>
▲This means that the following reduced system of equations<br>
▲ x + 10z = 5<br>
▲ y − 34z = −16<br>
▲ 0 +0 +0 = −3<br>
▲is equivalent to the original system. In other words, the two have the same solutions. <br>
▲But this last system clearly has no solution (the last equation requires that x, y and z satisfy 0x+0y+0z = −3,<br>
▲and no such numbers exist). <br>
▲Hence the original system has no solution.<big>Big text</big>
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