Activity 1

Below are four matrices. See if you can use elementary row operations to put them in echelon form (then see if you can read off the solutions!):

$A_1$	$A_5$	$A_6$
$$ \begin{bmatrix} 2&-1&4\\ 4&1&10\\ -2&7&10 \end{bmatrix} $$	$$ \begin{bmatrix} 3&-1&4\\ 6&-4&12\\ -3&-11&20 \end{bmatrix} $$	$$ \begin{bmatrix} 2&-1&4&1\\ 4&-1&11&6\\ -2&7&10&25 \end{bmatrix} $$