title: Applying sqrt function on a column
body: <p>I have following data frame</p>
  
  <pre><code>data = {'year': [2010, 2011, 2012, 2011, 2012, 2010, 2011, 2012],
                  'team': ['Bears', 'Bears', 'Bears', 'Packers', 'Packers', 'Lions', 'Lions', 'Lions'],
                  'wins': [11, 8, 10, 15, 11, 6, 10, 4],
                  'losses': [5, 8, 6, 1, 5, 10, 6, 12]}
  
  football = pd.DataFrame(data, columns=['year', 'team', 'wins', 'losses'])
  football.set_index(['team', 'year'], inplace=True)
  </code></pre>
  
  <p>How I can apply <code>sqrt</code> function after I do sum to the columns?</p>
  
  <pre><code>football[['wins', 'losses']].sum(axis=1)
  </code></pre>