Với `xge0` `;` `xne1` ta có :
`P=sqrtx/(sqrtx-1) +3/(sqrtx+1)-(6sqrtx-4)/(x-1)`
`=(sqrtx(sqrtx+1))/(x-1) +(3(sqrtx-1))/(x-1) -(6sqrtx-4)/(x-1)`
`=(x+sqrtx+3sqrtx-3-6sqrtx+4)/(x-1)`
`=(x-2sqrtx+1)/(x-1)`
`=((sqrtx)^2-2·sqrtx ·1+1^2)/(x-1)`
`=(sqrtx -1)^2/((sqrtx-1)(sqrtx+1))`
`=(sqrtx-1)/(sqrtx+1)`
Vậy với `xge0` `;` `xne1` thì `P=(sqrtx-1)/(sqrtx+1)`