1) x (x+2)(x-2)-x (x^2-8)=16
x (x^2-4)-x (x^2-8)=16
x^3-4x-x^3+8x=16
4x=16
x=4
2) 2y (4y-1)-2 (3-2y)^2=48
8y^2-2y-2 (9-12y×4y^2)=48
8y-2y-18+24y-8y^2=48
22y-18=28
22y=66
y=3
3) x^2 (x+2)-x (x+1)^2=5x+9
x^3+2x^2-x (x^2+2x+1)=5x+9
x^3+2x^2-x^3-2x^2-x=5x+9
-x=5x+9
-6x=9
6x=-9
x=-1.5
4)(y-3)^2+3 (y+2)(y-2)=9+4y^2
y^2-6y+9+3 (y^2-4)=9+4y^2
y^2-6y+9+3y^2-12=9+4y^2
4y^2-6y-3=9+4y^2
4y^2-6y-4y^2=9+3
-6y=-12
y=-2