a)
`x=15/(sqrt6-1)-2/(sqrt6+2)`
`=3sqrt6+3−sqrt6+2`
`=2sqrt6+5`
`A=x/(sqrtx-1)-(2x-sqrtx)/(x-sqrtx)`
`=x/(sqrtx-1)-(sqrt(2sqrtx-1))/(sqrtx(sqrtx-1))`
`=x/(sqrtx-1)-(2sqrtx-1)/(sqrtx-1)`
`=(x-2sqrtx+1)/(sqrtx-1)`
`=(sqrtx-1)^2/(sqrtx-1)`
`=sqrtx-1`
b)
`B=(A+1)(sqrt3-sqrt2)`
`=(sqrtx-1+1)(sqrt3-sqrt2)`
`=sqrtx(sqrt3-sqrt2)`
`=sqrt(2sqrt6+5)(sqrt3-sqrt2)`
`=(sqrt3+sqrt2)(sqrt3-sqrt2)`
`=3-2`
`=1`
