title: How can I draw a linear regression line in this graph?
body: <p><a href="https://i.stack.imgur.com/fto1M.png" rel="nofollow noreferrer">enter image description here</a>How can I draw a linear regression line in this graph?</p>
  
  <p>here is my code:</p>
  
  <pre><code>import numpy as np
  import pandas_datareader.data as web
  import pandas as pd
  import datetime
  import matplotlib.pyplot as plt
  #get adjusted close price of Tencent from yahoo
  start = datetime.datetime(2007, 1, 1)
  end = datetime.datetime(2017, 12, 27)
  tencent = pd.DataFrame()
  tencent = web.DataReader('0700.hk', 'yahoo', start, end)['Adj Close']
  nomalized_return=np.log(tencent/tencent.iloc[0])
  nomalized_return.plot()
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/fto1M.png" rel="nofollow noreferrer">Pic 1 Jupiter Notebook</a></p>
  
  <p><a href="https://i.stack.imgur.com/krHQi.png" rel="nofollow noreferrer">Pic 2 my Jupiter Notebook</a></p>