I'm not sure if I just hit my limit for the day regarding Calc, but I may have. I was wondering if someone could take a look at this problem for me. I have the solution in front of me, with most of the steps, but I don't see how to go from the last step to the conclusion.

The problem is stated:

If x^2-xy+y^2=3, find y' and y".

2x-xy'-y+2yy'=0

I just don't see how to go from the

to 18/(x-2y)^3

Is there something that is incredibly obvious that I am missing, or is it just another problem with this book? (I have found a few errors already)

Thank you! Any input would be appreciated.