x=x1
所以x1²=-3x1-1
x1³=x1*x1²
=x1(-3x1-1)
=-3x²-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明白了