Подстановка условия
[src]y^2 - (8 - y)*(y + 8) при y = -1/3
$$y^{2} - \left(- y + 8\right) \left(y + 8\right)$$
(-1/3)^2 - (8 - (-1/3))*((-1/3) + 8)
$$(-1/3)^{2} - \left(- (-1/3) + 8\right) \left((-1/3) + 8\right)$$
(-1/3)^2 - (8 - (-1)/3)*(-1/3 + 8)
$$- \left(- \frac{1}{3} + 8\right) \left(- \frac{-1}{3} + 8\right) + \left(- \frac{1}{3}\right)^{2}$$