13.已知函数f(x)=2x−12x+1+3x+1f(x)=\frac{{2^x}-1}{{2^x}+1}+3x+1f(x)=2x+12x−1+3x+1,且f(a2)+f(3a−4)<2f(a^{2})+f(3a-4)<2f(a2)+f(3a−4)<2,则实数aaa的取值范围为((( )))