The equation x2y2−9y2+6x2y+54y=0 represents

We havex2y2−9y2−6x2y+54y=0or y2(x2−9)−6y(x2−9)=0or y(y−6)(x−3)(x+3)=0or y=0, y=6, x=3, x=−3So, the given equation represents four straight lines which form a square