已知m^2-5m-1=0,m^2-2*2.5m+2.5^2-2.5^2-1=0,(m-2.5)^2=7.25,m-2.5=√7.25,或 m-2.5=-√7.25,m1=2.5+√7.25,m2=2.5-√7.25,则2m^2-5m+1/m^2=2*(2.5+√7.25)^2-5*(2.5+√7.25)+1/(2.5+√7.25)^2==2*(6.25+5√7.25+7.2...