Đáp án+Giải thích các bước giải:
`a)B=(sqrtx+1)/(sqrtx-3)+(2sqrtx)/(sqrtx+3)+(2+5sqrtx)/(9-x)(x>=0,x ne 9)`
`B=((sqrtx+1)(sqrtx+3)+2sqrtx(sqrtx-3)-5sqrtx-2)/((sqrtx-3)(sqrtx+3))`
`B=(x+4sqrtx+3+2x-6sqrtx-5sqrtx-2)/((sqrtx-3)(sqrtx+3))`
`B=(3x-7sqrtx+1)/(x-9)`
`b)B=3`
`<=>3x-7sqrtx+1=3x-27`
`<=>-7sqrtx+1=-27`
`<=>-7sqrtx=-28`
`<=>sqrtx=4`
`<=>x=16(tmdk)`
