Hint 2

I flagged it as good because it is a good hint, but are students taught how they can use this information to lead them to the normal equations? Are students even taught that this is what the least squares method does. I'm just not sure how helpful it is because I'm not sure what the curriculum is like.

I don't assume they know how to derive the normal equations from this. I hope they do know that this is what least squares is about. A major benefit of this hint is that it introduces the \hat{x} notation.