в) $$y = x^7 - 4x^5 + 2x - 1$$
$$y' = (x^7)' - (4x^5)' + (2x)' - (1)' = 7x^6 - 20x^4 + 2 - 0 = 7x^6 - 20x^4 + 2$$
Ответ: $$y' = 7x^6 - 20x^4 + 2$$