(1/2)^1-3x=4^2x-1化为
2^(3x-1)=2^(4x-2)
3x-1=4x-2
x=1
9^x-(4*3^x+1) +27=0,设3^x=t,原式化为
t^2-12t+27=0
(t-9)(t-3)=0
t=9或t=3
3^x=9,解得x=2
3^x=3,解得x=1