分母是x²-4吧,不然化简不了
4-4x+x²/x-4
=(x-2)²/(x-4)
=(-5-2)²/(-5-4)
=-49/9
分母是x²-4的话
原式＝(x-2)²/(x+2)(x-2)
=(x-2)/(x+2)
=(-5-2)/(-5+2)
=7/3