7.(2021春•利通区校级月考)已知函数f(x)=ex−e−x−2xf(x)=e^{x}-e^{-x}-2xf(x)=ex−e−x−2x,若不等式f(ax2)+f(1−2ax)⩾0f(ax^{2})+f(1-2ax)\geqslant 0f(ax2)+f(1−2ax)⩾0对∀x∈R\forall x\in R∀x∈R恒成立,则实数aaa的取值范围是((( )))