Find dy/dx by implicit differentiation

1. x^3 -xy+ y^2= 7

The given answer is (y-3x^2)/ (2y-x), but I'm not getting it.

2. How would I do this one? If I couldn't do the above one, which looks a heck of a lot simpler, I doubt I'll get through this one.

x^ (6/7) + y^ (8/5) = 16

2 answers

x^3 -xy+ y^2= 7
3x^2-xdy/dx-y+2ydy/dx=0

dy/dx(2y-x)=y-3x^2

Why is it you cannot get the answer?

x^ (6/7) + y^ (8/5) = 16
6/7 x^(-2/7) + 8/5 y^(3/5)y'=0

y'= (-6/7 x^(-2/7))/(8/5 y^)3/5))

do you agree?
you may need to adjust for the fact that 6/7 - 1 = -1/7, not -2/7