Алгебра 7 класс, Дорофеев. №695

а) a (a+b) - b (a-b)

б) 2x (x-y) - y (y-2x)

в) a (a^2 - 1) + a^2 (a-1)

г) 4m (m-2) - (4m^2-8)

д) 2 (x^2-7) + (7-2x^2)

е) 3x (x-y) + 3y (x+y)

а) a (a+b) - b (a-b) = (a-b) (a+b) (a-b)

б) 2x (x-y) - y (y-2x) = (2x-y) (x-y) (y-2x) = (y-x) (2x-y) (2x-y) = (y-x) (2x-y) ²

в) a (a ² - 1) + a ² (a-1) = (a+a ²) (a-1) (a+1) (a-1) = a (1+a) (a-1) (a+1) (a-1) a (a²-1) ²

г) 4m (m-2) - (4m ² - 8) = 4m (m-2) - 4m (m-2) = 0

д) 2 (x ² - 7) + (7-2x ²) = 2x ² - 14 + 7 - 2x² = - 7

е) 3x (x-y) + 3y (x+y) = 3x+3y (x-y) (x+y) = 3 (x+y) (x-y) (x+y)