Bài 11
a) Rút gọn
= [(√x+2)/(√x+1)^2 - (√x-2)/(x-1)] . √x+1/√x
= [(√x+2)(√x-1)/(√x+1)^2(√x-1) - (√x+1)(√x-2)/(√x+1)(x-1)] . √x+1/√x
= [(x - √x + 2√x - 2 - x + 2√x - √x + 2) / (√x+1)(x-1)] . √x+1/√x
= 2√x/(√x+1)(x-1) . √x+1/√x
= 2/(x-1)

Q = √x+2)(x-1) / (√x+2)^2(x-1)    -      (√x-2)(√x+2)^2 / x-1)(√x+2)^2      *       √x+1/√x
= x - √x + 2√x - 2 - (√x-2)(x + 2√x+4)  / (x-1)(√x+2)^2        *     √x+1/√x
= x + √x - 2 - x√x-2x- 4√x + 2x + 4√x + 8 / (x-1)(x+2)^2        * x+1/√ x
= x - x√x  +√x + 6 / (x-1)(√x+2)^2  * √x+1/√x