b) `B=(\sqrt10-\sqrt2)\sqrt(3+\sqrt5)`
`B=[\sqrt2(\sqrt5-1)]\sqrt(3+2\sqrt5)`
`B=(\sqrt5-1)\sqrt(6+2\sqrt5)`
`B=(\sqrt5-1)\sqrt[(\sqrt5+1)^2]`
`B=(\sqrt5-1)(\sqrt5+1)`
`B=5-1=4`
d) `D=(1/(\sqrtx+2)+1/(\sqrtx-2)). (\sqrtx-2)/(\sqrtx)`
`D=(2\sqrtx)/[(\sqrtx-2)(\sqrtx+2)]. (\sqrtx-2)/(\sqrtx)`
`D=2/(\sqrtx+2)`