ok look dude when dy/dx=0 this means ur differentiation should be 0 i have done my differentiation as (2x+2y)/(-2x+6y) now throw the denominator away cuz u cnt divide anything by 0 and then take the nominator =0 as for the differentiantion to be 0 nomintor should be 0
soz 2x+2y=0 get the x to 0 or y to 0 and substitute in the equation final answer should be (0,sq root 16/3) (0,-sq root 16/3)