For a real parameter k, consider the quartic polynomial Fk(x)=x4−4kx2+k2.
a. (i) Show that the critical points of Fk(x) are the real solutions of x3−2kx=0.
b. (ii) Determine all real values of k for which Fk(x) possesses exactly two distinct local minima on the real line.
c. (iii) For the values of k obtained in part (ii), compute the coordinates of these local minima and the corresponding minimum values of Fk(x).