化简(x^2-4\x^2-4x+4+2-x\x+2).其中x=-3

问题描述:

化简(x^2-4\x^2-4x+4+2-x\x+2).其中x=-3

原式=(x+2)(x-2)/(x-2)^2-(x-2)/(x+2)
=(x+2)/(x-2)-(x-2)/(x+2)
=[(x+2)^2-(x-2)^2]/(x+2)(x-2)
=(x+2+x-2)(x+2-x+2)/(x+2)(x-2)
=4x/(x+2)(x-2)
=-12/[(-1)×(-5)]
=-12/5