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# I need help in a matrix problem

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I have this matrix A= $$\begin{bmatrix} 1 && -1 && 0 && 1 \\ 3 && 1 && -1 && 2 \\ 7 && 1 && -2 && 8 \end{bmatrix}$$ and i need to find matrix P,Q so that PAQ= $$\begin{bmatrix} Irxr&& 0 \\ 0 && 0 \end{bmatrix}$$ But i find after trades for lines the 3,4 element its 1 and this cannot change with trades at columns.I'm correct and if not where im wrong? Thank you!

https://ibb.co/h5Uj7f

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Nov 1, 2018

#1
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What is Irxr?

Nov 1, 2018
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its an identity matrix with unknown lines and columns

Dimitristhym  Nov 1, 2018
edited by Dimitristhym  Nov 1, 2018
#3
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So you're saying that PAQ is an identity matrix with an unknown number of columns?

Guest Nov 1, 2018
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No  identity matrix  will included in PAQ and all other will have 0 exp. Will be 3 lines and 4 and will have identity matrix 1x1 or 2x2 or 3x3 and all other its 0

Dimitristhym  Nov 1, 2018
edited by Dimitristhym  Nov 1, 2018
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Sorry, I just don't understand what you're trying to say

Guest Nov 1, 2018