По действиям:
1) x-2y - x+2y = x-2y - x+2y = (x-2y)(x-2y) - (x+2y)(x+2y)=
x²+2xy x² -2xy x(x+2y) x(x-2y) x(x+2y)(x-2y)
=x²-4xy+4y²-x²-4xy-4y² = -8xy = -8y = 8y
x(x+2y)(x-2y) x(x+2y)(x-2y) x² - 4y² 4y² - x²
2) 8y : 4y² = 8y * 4y² - x² = 2
4y²-x² 4y²-x² 4y²-x² 4y² y