先化简再求值:【1/(x-y)-1/(x+y)】÷(xy²)/(x²-y²),其中x=1-
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先化简再求值:【1/(x-y)-1/(x+y)】÷(xy²)/(x²-y²),其中x=1-根号2,y=1+根号2
![先化简再求值:【1/(x-y)-1/(x+y)】÷(xy²)/(x²-y²),其中x=1-](/uploads/image/z/7548548-68-8.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC%EF%BC%9A%E3%80%901%2F%EF%BC%88x-y%EF%BC%89-1%2F%EF%BC%88x%2By%EF%BC%89%E3%80%91%C3%B7%28xy%26%23178%3B%29%2F%EF%BC%88x%26%23178%3B-y%26%23178%3B%EF%BC%89%2C%E5%85%B6%E4%B8%ADx%3D1-)
【1/(x-y)-1/(x+y)】÷(xy²)/(x²-y²)
=[1/(x-y)-1/(x+y)]×(x+y)(x-y)/(xy²)
=(x+y)/(xy²-(x-y)/(Xy²)
=(x+y-x+y)/(xy²)
=2/(xy)
当x=1-√2,y=1+√2时
原式=2/[(1-√2)(1+√2)]
=2/(1-2)
=-2
=[1/(x-y)-1/(x+y)]×(x+y)(x-y)/(xy²)
=(x+y)/(xy²-(x-y)/(Xy²)
=(x+y-x+y)/(xy²)
=2/(xy)
当x=1-√2,y=1+√2时
原式=2/[(1-√2)(1+√2)]
=2/(1-2)
=-2
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