Đáp án+Giải thích các bước giải:
`a)B=(1+(x+sqrtx)/(sqrtx+1))(1+(x-sqrtx)/(1-sqrtx))(x>=0,x ne 1)`
`B=(1+(sqrtx(sqrtx+1))/(sqrtx+1))(1+(sqrtx(sqrtx-1))/(-(sqrtx-1)))`
`B=(1+sqrtx)(1-sqrtx)`
`B=1-x`
`b)x=1/(sqrt2+1)`
`x=(sqrt2-1)/((sqrt2+1)(sqrt2-1))`
`x=(sqrt2-1)/(2-1)=sqrt2-1`
`=>B=1-(sqrt2-1)=2-sqrt2`
`2)C=x/(sqrtx-1)-(2x-sqrtx)/(x-sqrtx)(x>0,x ne 1)`
`C=x/(sqrtx-1)-(sqrtx(2sqrtx-1))/(sqrtx(sqrtx-1))`
`C=x/(sqrtx-1)-(2sqrtx-1)/(sqrtx-1)`
`C=(x-2sqrtx+1)/(sqrtx-1)`
`C=(sqrtx-1)^2/(sqrtx-1)`
`C=sqrtx-1`
`b)x=6+2sqrt5`
`x=5+2sqrt5+1`
`x=(sqrt5+1)^2`
`=>C=sqrt{(sqrt5+1)^2}-1`
`C=sqrt5+1-1=sqrt5`