Here's a question from a past paper

I have attempted the first part and my values are:

K = +8 or -8 C = 2

Whereas the answer in the marking scheme states K = 32 and C = 2

Is there a mistake in the marking scheme because the value of K can't be 32 if the value of C is 2 ... right?

Thanks!

P.S

My equation of the curve comes out to be