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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