$$524384x^3−27204x^2y−40806xy^2−295763y^3=0$$ 

$$(8x−7y)(65568x^2+53954xy+42109y^2)=0$$
i.e, $$8x−7y=0$$

I just want to know how we reach from 1st line to 2nd line. I mean how to factorize it?
How $$8x-7y$$ got separated out?