## anonymous 3 years ago $y^2=2px$ $\Rightarrow 2ydy=2pdx$ How is this achieved at? I've always gone with calculating $2y\frac{dy}{dx}=2p$ and multiplying both sides by dx. But I know that's heresy. What's the official story as to how it's arrived at?

1. anonymous

I've always found it odd how it seems plucked out of thin air

2. anonymous

here is a link this is called differentials chew on it

3. anonymous

Oh differentials- I wasn't thinking!