title: Online tool for generating mathematical equation image files
body: <p>I'm looking for an online tool that will let me create a gif or png like this one:</p>
  
  <p><img src="https://upload.wikimedia.org/math/b/4/7/b477e400396c711c60c4302bbbd888ae.png" alt="alt text"></p>
  
  <p>Some kind of LaTex online service, with friendly examples?</p>