title: Plot 3D plane given equations in matlab
body: <p>I want to plot 2 3D planes for the equations given below :  </p>
  
  <pre><code>x + y + z = 1
  2x - y = 0
  </code></pre>
  
  <p>For 1st equation, I plotted it using <code>meshgrid</code> as :   </p>
  
  <pre><code>[x y] = meshgrid(-5:0.5:5);  
  z = 1 - x - y  
  mesh(x,y,z)
  </code></pre>
  
  <p>But for 2nd equation, z is not given i.e. z can be anything, then how do I plot plane for this ?  </p>