Is Matrix A Invertible? Solving Linear System with Gaussian Elimination

gpax42
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Homework Statement



Suppose that Gaussian Elimination gives the soluiton of a Linear System Ax=c as x = x0 + a1x1 + a2x2, where A is a 6X6 matrix and a1 and a2 are arbitrary. Is the matrix A invertible? Explain


The Attempt at a Solution



I simply explained that due to properties of an invertible matrix, Ax=c must have exactly one solution but if a1 and 2 are arbitrary, then x = x0 + a1x1 + a2x2 has infinitely many solutions and A cannot be invertible

does anyone agree with this answer and if not, any advice on how to start the problem would be great appreciated :redface: thanks a lot!
 
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I'm assuming that x0, x1, and x2 are vectors. Your reasoning looks fine to me. If A had been invertible then you would have gotten a unique solution, which could be written as x = A-1c.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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