title: Add a multivariate linear regression line on a ggplot using R
body: <p>I have created a scatter plot of the variables Y and X1 using ggplot.
  I would like to add the following linear regression line to the ggplot:</p>
  <pre><code>model &lt;- lm(Y ~ X1 + X2 + X3 + X4 + X5, dataframe)
  
  ggplot(dataframe, aes(x = X1, y = Y, col = X5)) +
    geom_point()
  </code></pre>
  <p>X5 is a dummy variable. I would like to add the linear regression line of X1 when all other variables are held constant</p>
  <p>How can this be done?</p>