1.x1,x2是方程x方+3x+1=0的两实数根,即x1^2+3x1+1=0x1^2+3x1=-1x1^2=-3x1-1根据根与系数关系得x1+x2=-3x1^3+8x2+20=x1*x1^2+8x2+20=x1*(-3x1-1)+8x2+20=-3x1^2-x1+8x2+20=-3x1^2-9x1+8x1+8x2+20=-3(x1^2+3x1)+8(x1+x...