(y-3)^3-(y+3)^3=9y(1-2y);
(y-3-y-3)((y-3)²+(y-3)(y+3)+(y+3)²)=9y(1-2y);
-6(y²+9-6y+y²-9+y²+9+6y)=9y(1-2y);
-18(y²+3)=9y(1-2y);
y=-6;
(y-3)^3-(y+3)^3=9y(1-2y);
(y-3-y-3)((y-3)²+(y-3)(y+3)+(y+3)²)=9y(1-2y);
-6(y²+9-6y+y²-9+y²+9+6y)=9y(1-2y);
-18(y²+3)=9y(1-2y);
y=-6;