2x²(x²-x+1)-x(2x^3-10x²-2x-3),其中x=-1/2
=2x^4-2x^3+2x^2-2x^4+10x^3+2x^2+3x
=8x^3+4x^2+3x
=8*(-1/2)^3+4*(-1/2)^2+3*(-1/2)
=-1+1-3/2
=-3/2