谁能帮忙求个方程组

此题无解啊，不信你看看：

t=-0.1:0.001:0.1
a1=solve('1-0.75-a^(3000*t)','a')
a2=solve('1-0.05-a^(5000*t)','a')
a1=subs(a1)
a2=subs(a2)
plot(t,a1,t,a2)
axis([-0.1 0.1 0.8 1.2])

solve('0.75-1+a^(3000*t)=0 ','0.95-1+a^(5000*t)=0','a','t')
Warning: Explicit solution could not be found.
> In solve at 140

ans =

[ empty sym ]