Hi

After after doing row reduction on matrix[1 3; 2 2]

what would you get?

Im checking if method is completely misguided.

Thanks.

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- Jun 12th 2013, 02:29 PMn22row echelong reduction qusetion-for examination
Hi

After after doing row reduction on matrix[1 3; 2 2]

what would you get?

Im checking if method is completely misguided.

Thanks. - Jun 12th 2013, 02:37 PMtopsquarkRe: row echelong reduction qusetion-for examination
- Jun 12th 2013, 03:10 PMn22Re: row echelong reduction qusetion-for examination
this matrix was formed in order to find an eigenvector or basis using a given eigenvalue .

got[1 3;0 -4] after some reductions ...which involved ensuring theres a zero beneath the first leading entry..

row2/-4 then gives [ 1 3 ;0 1]

now assigning parameters y=t

x=-3t;y=t

then [x ;y]=t[-3;1]

eigenvector then in [-3;1] - Jun 13th 2013, 05:45 AMHallsofIvyRe: row echelong reduction qusetion-for examination
Yes, that is correct for "row-reduction" but I don't know what you mean about "finding eigenvectors". You

**cannot**find eigenvectors (or eigenvalues) by row reduction!

In this particular problem, it is easy to see that $\displaystyle \begin{bmatrix}1 & 3\\ 0 & 1\end{bmatrix}\begin{bmatrix}-3 \\ 1\end{bmatrix}= \begin{bmatrix}0 \\ 1\end{bmatrix}$ which is NOT a multiple of ([3, 1]. [-3, 1] is NOT an eigenvector for this matrix!

(Here, the eigenvalues are $\displaystyle 1+\sqrt{3}$ and $\displaystyle 1- \sqrt{3}$. Eigenvectors corresponding to eigenvalue $\displaystyle 1+ \sqrt{3}$ are multiples of $\displaystyle [3, \sqrt{3}]$ and eigenvectors corresponding to eigenvalue $\displaystyle 1- \sqrt{3}$ are multiples of $\displaystyle [3, -\sqrt{3}]$).