3^x=a
(a-9)/(a-2)+8/(a-1)≥1
(a-9)/(a-2)+8/(a-1)-1≥0
(a²-a-9a+9+8a-16-a²+a+2a-2)/(a-2)(a-1)≥0
(a-9)/(a-2)(a-1)≥0
a=9 a=2 a=1
_ + _ +
----------------[1]--------------[2]-------------------[9]-------------------
1≤a≤2⇒1≤3^x≤2⇒0≤x≤log(3)2
a≥9⇒3^x≥9⇒x≥2
x∈[0;log(3)2] U [2;∞)