title: Python: how to print exponential equations in matplotlib?
body: <p>I need to print the following equation on matplotlib using <code>plt.text()</code>:</p>
  
  <p><code>y=1.5*exp(-0.5x)-0.05</code></p>
  
  <p>I've used this line, but my plot does not show the equation anywhere:</p>
  
  <pre><code>a=1.5
  b=-0.5
  c=-0.05
  plt.text(2, 2, '$y=%3.7sexp+%3.7sx+%3.7s$'%(a, b, c), fontsize=20)
  </code></pre>
  
  <p>What do you reckon is the problem? Or is there another fancy way of writing this equation, maybe using the exponential the way we were taught at school?</p>