title: solving nonlinear equations in Octave
body: <p>I am new to Octave and would like to know how to solve nonlinear equation. Here is an example equation</p>
  
  <pre><code>x^4-16x^3+61x^2-22x-12=0
  </code></pre>
  
  <p>Update:</p>
  
  <pre><code>w+x+y+1=3
  
  2w+3x+4y+5=10
  
  w-x+y-1=4
  </code></pre>
  
  <p>thanks</p>