title: Square roots in python
body: <pre><code>&gt;&gt;&gt; import math
  &gt;&gt;&gt; math.sqrt(4)
  2.0
  </code></pre>
  
  <p>Why does Python not give the negative square roots (as -2 is also a square root of 4)?<br>
  And how can I make Python to give out negative square roots?</p>