ĐKXĐ: $\begin{cases} \sqrt{x}-1 \ne 0\\ x\sqrt{x}+1 \ne 0\\ x-\sqrt{x}+1 \ne 0\end{cases}$ `<=> x \ne 1`
`C = 1/(\sqrt{x}-1) - 3/(x\sqrt{x}+1)+1/(x-\sqrt{x}+1)`
`=1/(\sqrt{x}-1)-3/((\sqrt{x}+1)(x-\sqrt{x}+1))+1/(x-\sqrt{x}+1)`
`=1/(\sqrt{x}-1) + (-3 + \sqrt{x}+1)/((\sqrt{x}+1)(x-\sqrt{x}+1)`
`=(x\sqrt{x}+1+(\sqrt{x}-2)(\sqrt{x}-1))/((\sqrt{x}-1)(\sqrt{x}+1)(x-\sqrt{x}+1)`
`= (x\sqrt{x}+1+x-3\sqrt{x}+2)/((\sqrt{x}-1)(\sqrt{x}+1)(x-\sqrt{x}+1)`
`= (x\sqrt{x}+x-3\sqrt{x}+3)/((\sqrt{x}-1)(\sqrt{x}+1)(x-\sqrt{x}+1)`
