y=(3x²+3x+3+1)/(x²+x+1)=[3(x²+x+1)+1]/(x²+x+1)=3+1/(x²+x+1)显然,当x²+x+1取最小值时,y取最大值令t=x²+x+1,开口向上,对称轴为x=-1/2的抛物线当x=-1/2时,t有最小值,min=3/4此...