rút gọn biểu thức A:

`P= (2/(sqrtx -1)-5/(x+sqrtx -2)): (1+ (3-x)/((sqrtx -1)(sqrtx +2)))`   `(đk: x ≥0; x ne 1)`

`= (2(sqrtx +2)-5)/((sqrtx -1)(sqrtx +2)): ((sqrtx -1)(sqrtx +2)+3-x)/((sqrtx -1)(sqrtx +2))`

`= (2sqrtx +4-5)/((sqrtx -1)(sqrtx +2)) : (x+sqrtx -2 +3-x)/((sqrtx -1)(sqrtx +2))`

`= (2sqrtx -1)/((sqrtx -1)(sqrtx +2)) :(sqrtx +1)/((sqrtx -1)(sqrtx +2))`

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

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

Vậy với `x ≥0; xne 1` thì `P= (2sqrtx -1)/(sqrtx +1)`