I attached the problem.

I'm totally confusing..

Can anyone help?

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- Jul 12th 2009, 07:53 PMqkfxjsbasis of null
I attached the problem.

I'm totally confusing..

Can anyone help? - Jul 12th 2009, 09:06 PMgconfused
First you should row reduce the matrix M into echelon form:

you should get:

$\displaystyle

B = \begin{bmatrix}1&2&1&3&0&0\\0&1&-1&2&-2&3\\0&0&0&1&1&-3\\0&0&0&0&1&-2\end{bmatrix}

$

For the basis of the column of M, you look at the pivot columns of B, these are the first, second, fourth, and fifth columns. Then you use these columns from M as the basis of column, so the answer for that should be:

$\displaystyle

Col M= \begin{bmatrix}1&2&-1&0\end{bmatrix}, \begin{bmatrix}2&5&-1&0\end{bmatrix},

$ yeahh those are meant to be written as vectors and don't forget the fourth and fifth columns

To find the basis of the Null M, you just have to solve $\displaystyle Mx= 0$

yeahhh and express the set via free variables, (you should have 2 free variables so the answer should be expressed using $\displaystyle x_3$ and $\displaystyle x_5$.

To find the basis of the Row of M, use the row echelon form. So the answer should be:

$\displaystyle

Row M = \begin{bmatrix}1&2&1&3&0&0\end{bmatrix},

\begin{bmatrix}0&1&-1&2&-2&3\end{bmatrix},$$\displaystyle

\begin{bmatrix}0&0&0&1&1&-3\end{bmatrix},

\begin{bmatrix}0&0&0&0&1&-2\end{bmatrix}

$

yupp that's it