先化简,再求值:x/x+2-x2;+2x+1/x+2÷x2;-1/x-1其中x=√3-2

题目

先化简,再求值:x/x+2-x2;+2x+1/x+2÷x2;-1/x-1其中x=√3-2

答案

x/x+2-x2;+2x+1/x+2÷x2;-1/x-1
=x/(x+2)-(x+1)^2/(x+2)÷(x+1)(x-1)/(x-1)
=x/(x+2)-(x+1)/(x+2)
=-1/(x+2)
=-1/(√3-2+2)
=-1/√3
=-√3/3
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