(MED SANTOS) Simplificando a expressão $\phantom{X}\dfrac{\,\sqrt{\dfrac{\,x\,}{\,y\,}\,}\,-\,\sqrt{\dfrac{\,y\,}{\,x\,}}\,}{\,\sqrt{\dfrac{1}{\,y\,}\,}\,-\,\sqrt{\dfrac{1}{\,x\,}}\,}\phantom{X}$ obtemos:
a)
$\;\dfrac{\,\sqrt{x\;}\,-\,\sqrt{y\;}\,}{\,xy\;}\;$
b)
$\;\sqrt{x\;}\,-\,\sqrt{y\;}\;$
c)
$\;\dfrac{\,xy\,}{\,x\,+\,y\,}\;$
d)
$\;\,\sqrt{x\,}\,+\,\sqrt{y\,}\;$
