x1²+3x1+1=0x1²=-3x1-1所以x1³=x1(-3x1-1)=-3x1²-x1=-3(-3x1-1)-x1=8x1+3且x1+x2=-3所以原式=8x1+3+8x2+20=8(x1+x2)+23=-24+23=-1
