解题思路:A-(B+C)=( x3-2x2+4x+3)-[(x2+2x-6)+( x3+2x-3)],先去小括号,再去中括号得到原式=x3-2x2+4x+3-x2-2x+6-x3-2x+3,合并同类项后得到原式=-3x2+12,然后把x=-2代入计算即可.
A-(B+C)=(x3-2x2+4x+3)-[(x2+2x-6)+(x3+2x-3)]
=(x3-2x2+4x+3)-[x2+2x-6+x3+2x-3]
=x3-2x2+4x+3-x2-2x+6-x3-2x+3
=x3-x3-2x2-x2+4x-2x-2x+3+3+6
=-3x2+12,
当x=-2时,原式=-3×(-2)2+12=-12+12=0.
点评:
本题考点: 整式的加减—化简求值.
考点点评: 本题考查了整式的加减-化简求值:先去括号,再合并同类项,然后把字母的值代入计算.