Let a be a non-zero constant. A curve is given by
x=t3−3at,
y=t4−4at2+2a2,
where t∈R.
a. (i) Obtain expressions for dxdy and dx2d2y in terms of t and a.
b. (ii) Show that the curve possesses points of inflection only when t2=a, and determine the corresponding coordinates in terms of a.
c. (iii) For a>0, find the equation of the tangent to the curve at each point of inflection and state whether the curve changes from concave upward to concave downward or vice-versa at those points.