How do you extrapolate using a linear regression line?

When we use regression line to predict a point whose x-value is outside the range of x-values of training data, it is called extrapolation.

In order to (deliberately) extrapolate we just use the regression line to predict values that are far from training data.

Note that extrapolation does not give reliable predictions because the regression line may not be valid outside the training data range.

To extrapolate using a linear regression line, you extend the line beyond the range of the observed data to predict values for independent variables that are beyond the observed range. This is done by applying the same linear relationship established by the regression line to values outside the observed range. However, it's important to note that extrapolation carries risks because it assumes that the linear relationship holds true even beyond the observed data, which may not always be the case.