mn giúp em vs ạ em cảm ơn nhìu lắm

Đáp án+Giải thích các bước giải:

a)

`(x\sqrtx+y\sqrty)/(\sqrtx+\sqrty)-\sqrt(xy)`
`=((\sqrtx)^3+(\sqrty)^3)/(\sqrtx+\sqrty)-\sqrt(xy)`
`=((\sqrtx+\sqrty)(x+y-\sqrt(xy)))/(\sqrtx+\sqrty)-\sqrt(xy)`
`=x+y-\sqrt(xy)-\sqrt(xy)`
`=x+y-2\sqrt(xy)`
b)

`(a+\sqrt(ab))/(b+\sqrt(ab))`
`=(\sqrta(\sqrta+\sqrtb))/(\sqrtb(\sqrta+\sqrtb))`
`=(\sqrta)/(\sqrtb)`
`=(\sqrt(ab))/(b)`

c)

`((x\sqrty+y\sqrtx)(\sqrtx-\sqrty))/(\sqrt(xy))`
`=(\sqrt(xy)(\sqrtx+\sqrty)(\sqrtx-\sqrty))/(\sqrt(xy))`
`=(\sqrtx+\sqrty)(\sqrtx-\sqrty)`
`=x-y`