(x^2+1)/(x+1)+3(x+1)/(x^2+1)=4设(x^2+1)/(x+1)=a,则a+3/a=4a^2-4a+3=0(a-2)^2=1a=3或1(x^2+1)/(x+1)=3x^2+1=3(x+1)x^2-3x-2=0(x-3/2)^2=17/4x=(3±√17)/2(x^2+1)/(x+1)=1x^2+1=x+1x(x-1)=0x=0或1所以方程的解为x1...