title: Elementary Row Operations
body: <pre><code>A=  
    3  4  6  1  
   -1  0  6  5  
    8  1  0  4  
   -1 -2  1  3   
  </code></pre>
  
  <p>How can I transform A to reduced row echelon form with using elementary row operations. I cannot solve because I can't use the <code>rref()</code> command.</p>