Parametric Question 1991 3u HSC q5b (1 Viewer)

[gamja]

i and ii are fine, but iii clearly is not.
I calculated the midpoint of QR to be (5/4, 1). I compared that with the point (t, t^2) in being in the same linear equation and tried to find a formula, but tragically didnt work :,(

Any ideas? Thanks

 

[jimmysmith560]

Would the following working help?