Với `x >= 0,x \ne 4` có:
`B=([\sqrt{x}+1]/[x-4]-[\sqrt{x}-1]/[x+4\sqrt{x}+4]).[4\sqrt{x}-8]/\sqrt{x}`
`B=[(\sqrt{x}+1)(\sqrt{x}+2)-(\sqrt{x}-1)(\sqrt{x}-2)]/[(\sqrt{x}-2)(\sqrt{x}+2)^2].[4(\sqrt{x}-2)]/\sqrt{x}`
`B=[x+2\sqrt{x}+\sqrt{x}+2-x+2\sqrt{x}+\sqrt{x}-2]/[(\sqrt{x}+2)^2]. 4/\sqrt{x}`
`B=[6\sqrt{x}]/[(\sqrt{x}+2)^2]. 4/\sqrt{x}`
`B=24/[(\sqrt{x}+2)^2]`