`A = ((sqrtx+1)/sqrtx - 2)*sqrtx/((sqrtx-1)(2x-2sqrtx))` `(x > 0)`
`= (x+1-2sqrtx)/sqrtx * (sqrtx)/((sqrtx-1)2sqrtx(sqrtx-1))`
`= (x-2sqrtx+1) * 1/((sqrtx-1)2sqrtx(sqrtx-1))`
`= (sqrtx^2-2sqrtx*1+1^2) * 1/((sqrtx-1)2sqrtx(sqrtx-1))`
`= (sqrtx-1)^2 * 1/((sqrtx-1)2sqrtx(sqrtx-1))`
`= (sqrtx-1) * 1/(2sqrtx(sqrtx-1))`
`= 1/(2sqrtx)`
...........................................
Giá trị của biểu thức `A` khi `x = 9(TMĐK)` :
`A = 1/(2sqrt9)`
`= 1/(2*3)`
`= 1/6`
