Với `x >= 0,x \ne 1` có:
`3/[\sqrt{x}+1]-1/[\sqrt{x}-1]+[x+5]/[x-1]`
`=[3(\sqrt{x}-1)-(\sqrt{x}+1)+x+5]/[(\sqrt{x}-1)(\sqrt{x}+1)]`
`=[3\sqrt{x}-3-\sqrt{x}-1+x+5]/[(\sqrt{x}-1)(\sqrt{x}+1)]`
`=[x+2\sqrt{x}+1]/[(\sqrt{x}-1)(\sqrt{x}+1)]`
`=[(\sqrt{x}+1)^2]/[(\sqrt{x}-1)(\sqrt{x}+1)]`
`=[\sqrt{x}+1]/[\sqrt{x}-1]`