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Question from Anna, a student:

Perform row operations on the augmented matrix as far as necessary to determine whether the system is independent, dependent, or inconsistent.

x + y + z = 11
x - y + 3z = 5
2x + 2y + 2z = 15

Thank you!

Anna,

Have a look at my response to Karlena's question a while ago. Her system has exactly one solution so the rows of the augmented matrix are linearly independent.

Notice that after performing some row operations I wrote the resulting matrix back in equation form. If the final matrix had been

1
1
2
30
0
1
-2
-7
0
0
0
8

then the corresponding equations woud be

x + y + 2z = 30
y - 2z = -7
0 = 8

which is clearly impossible, zero is not equal to eight. If row operations on the augmented matrix result in a row of the form

0
0
0
k

where k is not zero, then the system of equations is inconsistant.

If row operations on the augmented matrix result in a row of the form

0
0
0
0

then you havs shown that one row of the matrix is a linear combination of the other rows and hence the rows are linearly dependent.

Row reduce your matrix and see which of the situations you have.

Harley

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