x>1则x-1>0原式=(x²-x)/(x-1)+3/(x-1)=x(x-1)/(x-1)+3/(x-1)=x+3/(x-1)=(x-1)+3/(x-1)+1≥2√[(x-1)*3/(x-1)]+1=2√3+1所以最小值是2√3+1
