I've got a one mark question on an assignment, so 'logic' dictates that it should be simple, right? But I just don't get it.

I've got the variable point P(2at,at^2), which lies on the parabolax^2=4at

I've already proven that the equation of the normal at P isx+ty=at^3+2at

Now, based on that, I have to find the co-ordinates of Q (also on the parabola), whose normal is perpendicular to the normal at P.

The next part of the assignment gives me the point at which the two normals intersect (R(a[t-1/t] ,a[t^2+1+1/t^2]),so I know that the equation of QR isy=tx+a/t^2+a, but I seeing as that is backwards-engineering from a 4 mark question, there's got to be something I'm missing in the "find Q" one.