3x^2-[7X-(4X-3)-2X^2]
=3x^2-[7X-4X+3-2X^2]
=3x^2-7X+4X-3+2X^2
=5x^2-3x-3若x=-1，该题的答案是什么？若x=-1则原式=5*(-1)^2-3*(-1)-3 =5+3-3 =5