已知A=x^3-2x^2+4x+3,B=x^2+2x-6,C=x^3+2x-3,求A-(B+C)的值,其中x=-2.

已知A=x^3-2x^2+4x+3,B=x^2+2x-6,C=x^3+2x-3,求A-(B+C)的值,其中x=-2.

A-(B+C)
=x³-2x²+4x+3-(x²+2x-6+x³+2x-3)
=x³-2x²+4x+3-x²-4x-x³+9
=-3x²+12
=-3*(-2)²+12
=-12+12
=0