Rút gọn : ( 1/(x- căn x) + 1/(căn x -1)): căn x/(x- 2căn x+1)

Đặt `A=(1/(x-sqrtx)+1/(sqrtx-1)):sqrtx/(x-2sqrtx+1)`

`đk:x>0,x ne 1`

`A=((1+sqrtx)/(x-sqrtx)).(x-2sqrtx+1)/sqrtx`

`=((1+sqrtx)/(sqrtx(sqrtx-1))).(sqrtx-1)^2/sqrtx`

`=((1+sqrtx)(sqrtx-1))/x`

`=(x-1)/x.`