`\qquad B=(2sqrt{x}-9)/(x-5sqrt{x}+6)-(sqrt{x}+3)/(sqrt{x}-2)-(2sqrt{x}+1)/(3-sqrt{x})`
Với `x>=0;x\ne4;x\ne9` thì:
`B=(2sqrt{x}-9)/((sqrt{x}-2)(sqrt{x}-3))-(sqrt{x}+3)/(sqrt{x}-2)+(2sqrt{x}+1)/(sqrt{x}-3)`
`B=(2sqrt{x}-9-(sqrt{x}+3)(sqrt{x}-3)+(2sqrt{x}+1)(sqrt{x}-2))/((sqrt{x}-3)(sqrt{x}-2))`
`B=(2sqrt{x}-9-(x-9)+2x-4sqrt{x}+sqrt{x}-2)/((sqrt{x}-3)(sqrt{x}-2))`
`B=(2x-sqrt{x}-11-x+9)/((sqrt{x}-3)(sqrt{x}-2))`
`B=(x-sqrt{x}-2)/((sqrt{x}-3)(sqrt{x}-2))`
`B=(x-2sqrt{x}+sqrt{x}-2)/((sqrt{x}-3)(sqrt{x}-2))`
`B=((sqrt{x}-2)(sqrt{x}+1))/((sqrt{x}-3)(sqrt{x}-2))`
`B=(sqrt{x}+1)/(sqrt{x}-3)`
Vậy `B=(sqrt{x}+1)(sqrt{x}-3)` với `x>=0;x\ne4;x\ne9`