y(x) = - 7x - 1
y(a + 1) = - 7 * (a + 1) - 1 = - 7a - 7 - 1 = - 7a - 8
y(a) = - 7a - 1
y(a + 1) - y(a) = - 7a - 8 - (- 7a - 1) = - 7a - 8 + 7a + 1 = - 7
ответ : y(a + 1) - y(a) = - 7
