Подстановка условия
[src](8*a)/a2 - b2 + 3/b - a - 4/a + b при a = -1/2
(8*a)/a2 - b2 + 3/b - a - 4/a + b
b+−a+a28a−b2+b3−a4 (8*(-1/2))/a2 - b2 + 3/b - (-1/2) - 4/(-1/2) + b
b+−(−1/2)+a28(−1/2)−b2+b3−(−1/2)4 (8*(-1)/2)/a2 - b2 + 3/b - (-1)/2 - 4/(-1/2) + b
b+−b2+a2−41+b3−−21−−8 17/2 + b - b2 - 4/a2 + 3/b
b−b2+217+b3−a24