-1 -------- 2 (x - 5)
-1/(x - 5)^2 при x = -4
-1/(x - 5)^2
-1/((-4) - 5)^2
-1/(-4 - 5)^2
-1/81
-1/(-5.0 + x)^2
-1 -------------- 2 25 + x - 10*x