a) `x-2\sqrt{x}=3``(ĐK:xge0)`
`->x-2\sqrt{x}-3=0`
`->(\sqrt{x}+1)(\sqrt{x}-3)=0`
`->`\(\left[ \begin{array}{l}\sqrt{x}+1=0\\\sqrt{x}-3=0\end{array} \right.\)
`->`\(\left[ \begin{array}{l}x=∅\\x=9\end{array} \right.\)
Vậy `S={9}`
b)`\sqrt{4x-8}-1/3\sqrt{9x-18}+\sqrt{x-2}=6``(ĐK:xge2)`
`->2\sqrt{x-2}-3/3\sqrt{x-2}+\sqrt{x-2}=6`
`->2\sqrt{x-2}=6`
`->\sqrt{x-2}=3`
`->x-2=9`
`->x=11`
Vậy `S={11}`
