25．已知函数f(x)=x3+x+1+sinxf(x)=x^{3}+x+1+\sin xf(x)=x3+x+1+sinx，若f(a−1)+f(2a2)⩽2f(a-1)+f(2a^{2})\leqslant 2f(a−1)+f(2a2)⩽2，则实数aaa的取值范围是___[−1[-1[−1[，]12]\frac{1}{2}]21]___．