通分：(x^2+x^2 * (x+1)^2)/(x+1)^2=3.x^2+(x^4+2x^3+x^2)=3(x+1)^2.x^4+2x^3+2x^2=3x^2+6x+3.x^4+2x^3-x^2-6x-3=0.因式分解：(x^2-x-1)(x^2+3x+3)=0.后者Delta<0，无实根；前者有2个实根(1+√5)/2、(1-√5)/2.
