How do you differentiate #x^2+y^2=2xy#?
Saikiran Reddy and Kwasi F. give excellent solutions to this. The answer,
That's the same as the derivative of a linear function with slope,
If we have
The we must also have:
Factoring gets us:
And the only way for that to happen is to have:
(Which we already knew by differentiating, but this may be of interest as well.)