Đáp án+Giải thích các bước giải:
`a) (a+b-2sqrt{ab})/(sqrta-sqrtb):1/(sqrta+sqrtb)`
`=(a-2sqrt{ab}+b)/(sqrta-sqrtb):1/(sqrta+sqrtb)`
`=((sqrta-sqrtb)^2)/(sqrta-sqrtb):1/(sqrta+sqrtb)`
`=(sqrta-sqrtb).(sqrta+sqrtb)`
`=a-b`
`b) (2+(a-sqrta)/(sqrta-1)).(2-(a+sqrta)/(1+sqrta)`
`=[2+(sqrta(sqrta-1))/(sqrta-1)].[2-(sqrta(sqrta+1))/(1+sqrta)]`
`=(2+sqrta)(2-sqrta)`
`=4-a`
`c) (1/(x-sqrtx)+1/(sqrtx-1)):(sqrtx+1)/(x-2sqrtx+1)`
`=[1/(sqrtx(sqrtx-1)``+1/(sqrtx-1)]` `: (sqrtx+1)/((sqrtx-1)^2)`
`=[1/(sqrtx(sqrtx-1)``+sqrtx/(sqrtx(sqrtx-1))]``:(sqrtx+1)/((sqrtx-1)^2)`
`=[(1+sqrtx)/(sqrtx(sqrtx-1))].((sqrtx-1)^2)/(sqrtx+1)`
`=((1+sqrtx)(sqrtx-1)^2)/(sqrtx(sqrtx-1)(sqrtx+1))`
`=(sqrtx-1)/sqrtx`
