2^2x-2^x+1=(2^x)^2-2^x+1=9
设 2^x =a
a^2－a+1=9
(a-1/2)^2+3/4=9
(a-1/2)^2=9-3/4=33/4
a-1/2=1/2*√33
a=(1+√33)/2
2^x=a=(1+√33)/2