what's invariant tuples why is $f$ invariant which statement can be made when the function $f$ is invariant which of the following is an example of a function that is invariant? which linear regression is an example of an undigested tuple? when $f$ is an invariant function, why is $$ invariant when it represents an unknown function when is an estimator used that is invariant? what is $f$ in linear regression what is the tuple of $f$ if $$ is a tuple what is it where is x_i what is the function of $f$ what is the function for $f$ which linear tuples are invariant what is the function of the $f$ what is $f(ex_i)? what is an unordered function how do we find $f$ what kind of function is $f