2019-수학-가형-홀수-9¶
문제¶
풀이¶
from sympy import *
x = symbols('x')
y = Function('y')(x)
f=1/(1+exp(-x))
f.subs(x,-1)
\[\displaystyle \frac{1}{1 + e}\]
roots =solve(Eq(x,f.subs({x:y})),y)
g=roots[0]
g
\[\displaystyle \log{\left(- \frac{x}{x - 1} \right)}\]
factor(diff(g,x).subs({x:f.subs(x,-1)}))
\[\displaystyle \frac{\left(1 + e\right)^{2}}{e}\]