mik lm hộ 2 phần đầu nha
`1)`
`a)x>=0`
`b)x>=1`
`c)x>=0`
$d)\begin{cases}x\le1\\x\ge-1\end{cases}$
`2)`
`a)2sqrt2+sqrt18-sqrt32`
`=2sqrt2+3sqrt2-4sqrt2`
`=sqrt2`
`b)2sqrt5+sqrt((1-sqrt5)^2)`
`=2sqrt5+|1-sqrt5|`
`=2sqrt5+sqrt5-1`
`=3sqrt5-1`
`c)1/(sqrt3+1)+1/(sqrt3-1)-2sqrt3`
`=(sqrt3-1+sqrt3+1)/((sqrt3-1)(sqrt3+1))-2sqrt3`
`=(2sqrt3)/(3-1)-2sqrt3`
`=(2sqrt3)/(2)-2sqrt3`
`=sqrt3-2sqrt3`
`=-sqrt3`
