Parametric Rectangular Hyperbola Question!?

ahhh this is madness. I got the answer to Part A too, but I'm not so sure about B. lol so I kinda gave up, but the only other thing I can suggest is to take the derivative of the function that defines point Q to find the rate of change of that and slowly start to calculate new values based on the rate at which it's changing...if that even made sense.