求高手简便计算二次根式1.｛【（x√y）-（y√x）】/【（x√y）+（y√x）】｝-｛【（y√x）+（x√y）】/【（

｛【（x√y）-（y√x）】/【（x√y）+（y√x）】｝-｛【（y√x）+（x√y）】/【（y√x）-（x√y）】｝
=[(x√y-y√x)²+(x√y+y√x)²]/[(x√y-y√x)(x√y-y√x)]
=(x²y-2xy√xy+y²x+x²y+2xy√xy+y²x)/(x²y-y²x)
=2xy(x+y)/xy(x-y)
=2(x+y)/(x-y)
【（a-b）/（√a-√b）】-【（a+b-2√ab）/（√a-√b）】
=（√a-√b）（√a+√b）/（√a-√b）-（√a-√b）²/（√a-√b）
=√a+√b-(√a-√b)
=2√

1,计算的 ｜. 根号10*根号27 ⒉ (15根号12)/(2根号45) з (3根号01 3根号30 2 根号15 3 7.2 4 3/2 5 3根号30 6 2|a| 1 8/7