Let's find the inflection points, we'll need to solve the equation for this
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(the second derivative equals zero),
the roots of this equation will be the inflection points for the specified function graph:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
the second derivative$$\frac{2 e^{x} - \frac{\left(e^{x} + 1\right)^{2}}{x + e^{x}}}{4 \sqrt{- x - e^{x}}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = 0.490073068480548$$
$$x_{2} = 0.490073068480639$$
Сonvexity and concavity intervals:Let’s find the intervals where the function is convex or concave, for this look at the behaviour of the function at the inflection points:
Have no bends at the whole real axis