Matrices trouble, finding k so matrix is rank 2

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SUMMARY

The discussion focuses on determining the value of k for which the matrix A has a rank of 2. The matrix A is given as:
-4 9 14
2 7 16
-7 -2 k. Through row reduction, the user arrives at the form:
-4 9 14
0 23 46
0 0 92k + 2116. To achieve a rank of 2, the last row must equal zero, leading to the equation 92k + 2116 = 0. Solving this equation yields k = -23.

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mr_coffee
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Hello everyone, I have a problem...
I am suppose to Find the value of k for which the matrix:

A =
-4 9 14
2 7 16
-7 -2 k

has rank 2.
k = ?

I row reduced until i couldn't do it anymore and i got the following:
-4 9 14
0 23 46
0 0 92k + 2116

now I'm lost on how I'm suppose to find a value for k that will make this mantrix rank 2. ANy help would be great
 
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Just put 92k + 2116 = 0 since the rank of the matrix is determined by the number of non-zero rows when in row echelon form.
 

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