x1,x2为方程x²+3x+1=0的两个实数根x1²+3x1+1=0x1²=-(3x1+1)x1+x2=-3所以：x1³+8x2+20=-x1*(3x1+1)+8x2+20=-3x1²-x1+8x2+20=3*(3x1+1)-x1+8x2+20=8(x1+x2)+23=-24+23=-1如果您认可我的回答,...