Mong mn giúp đỡ mình ạ

`a)đkxđ:{(sqrtx>=0),(x-sqrtxne0),(2sqrtx+sqrtxne0):}`

`<=>{(x>=0),(sqrtx(sqrtx-1)ne0),(3sqrtxne0):}`

`<=>{(x>=0),(sqrtxne0),(sqrtx-1ne0):}`

`<=>{(x>=0),(xne0),(xne1):}`

`<=>{(x>0),(xne1):}`

`b)M=(xsqrtx-1)/(x-sqrtx):(x+sqrtx+1)/(2sqrtx+sqrtx)`

`=((sqrtx-1)(x+sqrtx+1))/(sqrtx(sqrtx-1)).(3sqrtx)/(x+sqrtx+1)`

`=(x+sqrtx+1)/sqrtx . (3sqrtx)/(x+sqrtx+1)`

`=3`

`c)M=3`

`=>AAx` thì `M` vẫn `=3`

`=>x=4-2sqrt3`thì`M=3`

Vậy `x=4-2sqrt3` thì `M=3`

`d)M=1` không thoả mãn