title: How to calculate the length of a curve of a math function?
body: <p>I got curve <code>C</code> and I want to compute the curve length between its 2 points <code>A,B</code>:</p>
  
  <pre><code>f(x) = x² + 2x
  C(   x,f(   x))
  A(-2.0,f(-2.0))
  B( 0.5,f( 0.5))
  </code></pre>
  
  <p>so <code>x=&lt;-2.0,0.5&gt;</code></p>
  
  <p><img src="https://i.stack.imgur.com/HZyVb.png" alt="img"></p>
  
  <p>How to calculate the curve length between points <code>A,B</code> ?
  Of course I want to know how to calculate it on sheets :)</p>
  
  <p>Thank you ;)</p>