$a)\sqrt[]{|x|-1}$
vì `|x|=x`
`=>` có nghĩa `<=>|x|-1>=0`
`<=>x#0`
`b)`$\sqrt[]{|x-1|-3}$
`|x-1|-3>=0`
`<=>|x-1|>=3`
có 2 th
th1 `x-1>=3`
`<=>x>=4`
th2 `x-1<=-3`
`<=>x<=-2`
từ 2 th `=>-2>=x=<4`
`c)` $\sqrt[]{4-|x|}$
có nghĩa `<=>4-|x|>=0`
`<=>|x|<=-4`
`<=>-4<=x=<4`
`d)`$\sqrt[]{x-2\sqrt[]{x-1}}$
`=`$\sqrt[]{x-1-2\sqrt[]{x-1+1}}$
`=`$\sqrt[]{(\sqrt[]{x-1}-1)^2}$
`<=>`$\sqrt[]{(\sqrt[]{x-1}-1)^2}$>=0`
`<=>`$\sqrt[]{x-1}-1>=0$
`<=>x>=1`
`e)` xđ `<=>9-12x+4x^2>0`
`<=>(2x-3)^2>=0`
vì `(2x-3)^2>=0(∀x)`
`=>2x-3#0`
`<=>x#3/2`
`h)` xđ
`<=>x+2`$\sqrt[]{x-1}>0$
`<=>x-1+2`$\sqrt[]{x-1}+1$
`<=>`$(\sqrt[]{x-1}+1)^2$
để có nghĩa `<=>` $\sqrt[]{x-1}>=0$
`<=>x>=1`
