Math Help - implicit differentiation.

1. implicit differentiation.

by differentiating, $x^2 + xy - 2y^2 = 0$ show that $\frac{dy}{dx} = 1$ or $\frac{-1}{2}$

Thanks

2. Implicit differentiation yields:

$2x + xy' + y - 4yy' = 0$

$xy' - 4yy' = -2x - y$

$y'(x - 4y) = -2x - y$

$y' = \frac{-2x - y}{x - 4y}$

That's as far as I can go without knowing more information.

3. that is the same with what I got.