(1)将x^2=x+1带入,可得x(x+1)^2-5x+2 =x^3+2x^2-4x+2,继续带入得x(x+1)+2(x+1)-4x+2=x^2-x+4 继续带入得x+1-x+4=5 (2)带入得x+1+1/(x+1)=(x^2+2x+2)/(x+1) 再带入得3(x+1)/(x+1)=3