`#AkaShi`
1) Đk: `a >= 0 ; a \ne 1`
` (1/(\sqrt{a}-1)+1/(\sqrt{a}+1))((a-1)/(\sqrt{a}+1)-2)`
`=((\sqrt{a}+1)/(a-1)+(\sqrt{a}-1)/(a-1))[(a-1)/(\sqrt{a}+1)-(2(\sqrt{a}+1))/(\sqrt{a}+1)]`
`=(\sqrt{a}+1+\sqrt{a}-1)/(a-1)*(a-1-2\sqrt{a}-2)/(\sqrt{a}+1)`
`=(2\sqrt{a})/(a-1)*(a-2\sqrt{a}-3)/(\sqrt{a}+1)`
`=(2\sqrt{a})/(a-1)*((\sqrt{a}+1)(\sqrt{a}-3))/(\sqrt{a}+1)`
`=(2a-6\sqrt{a})\t{a})/(a-1)`
.......................
`2) ` Đk: ` a >=0 ; a \ne 1`
`(a\sqrt{a}-1)/(a-\sqrt{a})-(a\sqrt{a}+1)/(a+\sqrt{a})+(a+1)/(\sqrt{a})`
`=((\sqrt{a})^3-1)/(a-\sqrt{a})-((\sqrt{a})^3+1)/(a+\sqrt{a})+(a+1)/(\sqrt{a})`
`=(a+\sqrt{a}+1)/(\sqrt{a})-(a-\sqrt{a}+1)/(\sqrt{a})+(a+1)/(\sqrt{a})`
`=(a+\sqrt{a}+1-a+\sqrt{a}-1+a+1)/(\sqrt{a})`
`=(a+2\sqrt{a}+1)/(\sqrt{a})`
`=((\sqrt{a}+1)^2)/(\sqrt{a})`
