∵a^2-2011a+1=0 ∴a^2+1=2011a ；a²-2011a=-1a^2－2010a+2011/(a^2+1) =a^2-(2011a-a)+2011/2011a=a²-2011a+a+1/a=-1+a+1/a(把a²-2011换成-1）=(a²-a+1)/a（通分）=(a^2-a+1)/a =(a^2+1-a)/a =...