Разложите на множители 28x^2-7y^2 -11x^2+22x-11 x^3+8y (y^2-1)-9

1) 7(4x² -y²) =7(2x -y)(2x +y)

2) -11(x² -2x +1) = -11(x -1)² = -11(x -1)(x -1)

3) x^3 -8y^3 =(x-2y)(x² +2xy +4y²)

4) (y²-1)² -9 =(y²-1 -3)(y²-1 +3) =(y² -4)(y² +2) =(y-2)(y+2)(y² +2)