# Which models of the data include interaction terms?

Recall from the video that interaction terms involve products of features.

Suppose we have two features x and y, and we use models that process the features as follows:

1. βx + βy + ββ
2. βxy + βx + βy
3. βx + βy + βx^2 + βy^2

where β is a coefficient in your model (not a feature).

Which expression(s) include interaction terms?