Giải thích các bước giải:
ĐKXĐ : `x>=2`
`sqrt(4x-8)+1/5 . sqrt(25x-50) - sqrt(x-2)=4`
`<=> sqrt(4(x-2))+1/5 . sqrt(25(x-2)) - sqrt(x-2)=4`
`<=> sqrt4 . sqrt(x-2) + 1/5 . sqrt25 . sqrt(x-2) - sqrt(x-2) = 4`
`<=> 2 sqrt(x-2) + sqrt(x-2) - sqrt(x-2) = 4`
`<=> 2 sqrt(x-2) = 4`
`<=> sqrt(x-2) = 2`
`<=> x-2 = 4`
`<=> x=6 \ \ \ \ \ text{(tm)}`
Vậy `S={6}`
