先化简,再求值先化简,再求值｛1-x／x+1-1｝÷2x／x²-1 ,其中x=1-√2

先化简,再求值先化简,再求值｛1-x／x+1-1｝÷2x／x²-1 ,其中x=1-√2
先化简,再求值先化简,再求值｛1-x／x+1-1｝÷2x／x²-1 ,其中x=1-√2

先化简,再求值先化简,再求值｛1-x／x+1-1｝÷2x／x²-1 ,其中x=1-√2
[(1-x)/(x+1)-1]÷2x／(x²-1)
=[(1-x-x-1)/(x+1)]÷2x／(x²-1)
=-2x/(x+1)÷2x／(x²-1)
=-2x/(x+1)*(x²-1)/2x
=-(x²-1)/(x+1)
=-(x-1)(x+1)/(x+1)
=-(x-1)
=1-x
=1-(1-√2 )
=1-1+√2
=√2