Đáp án+Giải thích các bước giải:
`sqrt{9x+18}-5sqrt{x+2}+4/5sqrt{25x+50}=6(x>=-2)`
`<=>3sqrt{x+2}-5sqrt{x+2}+4sqrt{x+2}=6`
`<=>2sqrt{x+2}=6`
`<=>sqrt{x+2}=3`
`<=>x+2=9`
`<=>x=7(tmđk)`
Vậy `S={7}.`
`5sqrt{x-5}+sqrt{9x-45}-sqrt{4x-20}=18(x>=5)`
`<=>5sqrt{x-5}+3sqrt{x-5}-2sqrt{x-5}=18`
`<=>6sqrt{x-5}=18`
`<=>sqrt{x-5}=3`
`<=>x-5=9`
`<=>x=14(tmđk)`
Vậy `S={14}.`
`sqrt{9x-27}+1/2sqrt{4x-12}-9sqrt{(x-3)/9}=2(x>=3)`
`<=>3sqrt{x-3}+sqrt{x-3}-3sqrt{x-3}=2`
`<=>sqrt{x-3}=2`
`<=>x-3=4`
`<=>x=7(tmđk)`
Vậy `S={7}.`
