2x(x-y)-(x2-xy)-4=
2x(x-y)-(x2-xy)-4=
2x kwadrat- 2xy- x kwadrat +xy - 4= x kwadrat- xy - 4 x kwadrat - xy-4
2x(x - y) - (x² - xy) - 4 = 2x² - 2xy - x² + xy - 4 = = x² - xy - 4
2x(x - y) - (x² - xy) - 4 = 2x² - 2xy - x² + xy - 4 = = x² - xy - 4