P and Q are the points with parameters p and q on the parabola x = at^2, y = 2at.
a) Show that the chord PQ is 2x - (p+q)y + 2apq = 0
b) If OP is perpendicular to OQ, show that the x-intercept of PQ is independent of p and q.
I need help with both, but I'm particularly confused with...