解：①原式=[(x-1)²+5(x-1)+8]/(x-1)=5-[(1-x)+8/(1-x)]≤5-2根号8=5-4根号2 ②原式=[(x-1)²+2(x-1)+2]/(x-1)=2+[(x-1)+2/(x-1)]≥2+2根号2
