16. Imagine you have two-dimensional dataset with totally non-correlated features. Can you use PCA to reduce dimensionality to 1D?

17. In what cases you might acquire better results with the PCA+LinearRegression instead of just directly running LinearRegression on original dataset? (5pts)

18. In what cases you might acquire worser results with the PCA+LinearRegression instead of just directly running LinearRegression on original dataset? (5pts)