2.(2023春•荔湾区期末)已知函数f(x)=axex−12(x+1)2,a∈Rf(x)=ax{e}^{x}-\frac{1}{2}(x+1)^{2},a\in Rf(x)=axex−21(x+1)2,a∈R.(1)讨论函数f(x)f(x)f(x)的单调性;