2^x=t
t > 0
2^(-x)=1/t
t+(1/t)-3 < 0
t^2-3t+1 < 0
D=(-3)^2-4=5
t1=(3-sqrt(5))/2 или t2=(3+sqrt(5))/2
____ (t1) ___-____ (t2) ___
t1 < t < t2
(3-sqrt(5))/2 < 2^x < (3+sqrt(5))/2
log_(2)(3-sqrt(5))/2 < x < log_(2) (3+sqrt(5))/2
О т в е т. (log_(2)(3-sqrt(5))/2; log_(2) (3+sqrt(5))/2)