Let ha(x)=x4−4ax2+16, where a is a real parameter.
(a) Compute ha′(x) and find every critical point in terms of a. Assume all work is shown.
(b) Determine all real values of a for which ha has exactly two distinct relative extrema. Provide algebraic justification based on the sign of ha′(x).
(c) For the values of a found in part (b), classify each extremum as a relative maximum or a relative minimum and state its x-coordinate.