计算:(1/x²-4x+4)-(x/x²-4)+(1/2x+4)=
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计算:(1/x²-4x+4)-(x/x²-4)+(1/2x+4)=
原式=1/(x-2)²-x/(x+2)(x-2)+1/2(x+2)
=(2x+4-2x²+4x+x²-4x+4)/]2(x+2)(x-2)²]
=(-x²+2x+8)/]2(x+2)(x-2)²]
=-(x-4)(x+2)/[2(x+2)(x-2)²]
=(4-x)/(2x²-8x+8)